Need help picking a primer

any of the aerosol can primers can be sprayed into it's own can cap, then poured into AB cup 

Depends what you are painting, & what you can get locally, so I ramble on with my thoughts & personal experience here.

Some use dime-store rattlecans, some use brand-name rattlecans, eg Halfords primer in the UK. ( This worked for me but anti-social to use indoors, seems to be cellulose based)

Certain Lacquer/Cellulose primers, although good for certain situations, are not people-friendly, & stink the house out.

Others use traditional enamels, eg Humbrol, are smelly as above, so consideration for your other half is needed!  

Some use Tamiya Acrylic Black, but I stopped using Tamiya 'cos I can't stand the smell & doesn't brush well for me.

So, assuming you are talking about plastic planes or Armour, I now use Vallejo polyeurathane primer, available in black, white or grey, especially if you have used resin, PE, or other mixed colour media.

lots of info here: http://www.acrylicosvallejo.com/gb/modelling-products-gb.html read about primers.

The polyeurathane primer sprays well, doesn't smell, cleans up quickly, & you can overpaint quickly (not me!) with acrylic or enamels.

I havent found a suitable airbrush ready primer. Not saying there isn't one out there, mind you.

Having said that I can eliminate a large part of your problem by telling you to avoid auto primers. I've found that they are usually the scratch filling variety and go on way to thick. So you have to thin and thin and thin to get them to air brush well. If you use them out of the can they have a tendency to fill detail and panel lines quickly.
People do use auto primers as you are finding out here but IMHO they are to much of a hassle.

Myself, I've used a couple of different primers in the airbrush. One is Mr. Surfacer 1200. I've thinned it with lacquer thinner and Mr Color thinner and found that in the end the stuff is a pain to spray. Sometimes it's worked well, sometimes the surface is really grainy and I have to sand it out. I don't have the paitience to keep dicking with it so I tried something else.

I tried Tamiya surface primer in the little square bottle. About the same result as above so I dropped that, only using it now to fill minor scratches with a brush then sanding it.

I finally tried Tamiya surface primer in a rattle can. It comes in "grades" and I was intrigued. I chose "fine" grade. Sprayed out of the can it shoots a little heavy so some trigger control goes a long way. I've decanted it and shot it unaltered through the airbrush and it sprays beautifully.
When it dries it dries to a perfectly smooth finish and requires no sanding for all but the most perfect of NMF jobs. And if you have to sand it? It polishes out like gloss paint. Actually, when left to dry on it's own it dries to a nice sheen, not a dead flat and rough finish like other primers I've used.

So, my advice is to obtain a rattle can of Tamiya surface primer. If you must airbrush, decant and spray away. Ventilate good, the stuff is not nose or lung friendly. Yes, it's more expensive. Yes, it's harder to find than Walmart rattle can. But my personal primer search ended when I found the stuff.

I have airbrushed the bottled Tamiya Liquid Surface Primer a few times (thinned with Tamiya lacquer thinner) and I thought it went down nicely.

I would simply decant some appropriately colored Model Master or regular Testors primer and use it in the airbrush.  I have been doing a bit of practicing with my el cheapo airbrush to get the technique down since I never had one until recently and it seems to work well.  One tip.  Get an empty baby food jar and put some saran (plastic) wrap over the top.  Then poke a hole big enough to kind of stick the spray head on the can through.  Stick the can head through it and then spray the paint into the jar.  The nice thing about doing this is that usually rattle can sprays are already thinned to the proper consistency, or close to it.  The baby food jars are great and nicely airtight when closed properly so they keep the paint fresh for quite a while.  Although on enamels I have noticed that the paint fumes tend to soften the wax seal in the lid and eventually it will leak air and the paint can dry out so don't keep it hanging around the shelf too long.

I use what ever light colored flat paint I have the most of. This can either be an acrylic or an enamel, depending on what I intend to do with the model paint wise.

Unless you have a color uniformity issue...such as a stark contrast between the color of your filler putty and the styrene you DO NOT have to cover the entire model with a solid coat of primer.

Primers serve two purposes...give visibility to any surface flaws in the plastic and to give the color coat a surface to grab on to.

A light misting of any flat color will identify such flaws as well as give you a suitable surface to which the color coat will bite onto.

Here I misted the known trouble areas to find any flaws...notice how little "primer" I used.

The one color that I normally give all of my aircraft as a "primer" once I have the real primer coat misted on is one of the aircraft's skin color...Aluminum. This way when in comes time to do realistic weathering, the base color is what is exposed once the paint is faded, scratched, scuffed and chipped away. Such as this Spitfire.

Aluminum serves not only as the skin color but it also provides color uniformity as a base for even light colors such as white, yellow, light gray or pale blue.

You're a modeler...thriftiness is a requirement! You don't need to use an expensive dedicated primer or a lot of any paint to prime a model for painting. If you were restoring a 1:1 scale subject...then yes as this is the first stage in corrosion prevention as well...but not for plastic models!

HawkeyeHobbies

You're a modeler...thriftiness is a requirement! 

Really? A requirement?

I've experimented with several primers since taking the hobby back up last summer. I'm a fan of Mr. Surfacer 1200, Tamiya Fine Surface Primer (the gray rattlecan decanted), and good old Model Master primer. I've had solid results with all three. I've also had terrible results with Tamiya's white primer, and will never use it again. Now when I need white, I put on a thin primer coat, then follow up with white enamel/acrylic/what-have-you.

At some point in the near future, I think I'm going to try priming with Tamiya's AS-12 bare-metal silver. Seems like it goes on smooth and very tough, and certainly easier for that "metal under paint" look than Alclad or other metalizers.

Thanks for all the help, and I said through an airbrush because I can get a thin layer so I dont clog up any surface details. Anyone have experience with the Alclad white surface primer and microfiller?

Laugh if you want but I use Krylon fusion primer - work's great for me !!! I find it goes on pretty flat and never have had any problem seeing detail afterwards.

No giggles here. That's stuff's made for plastic, sounds interesting.

For most projects I use Model Master Gray Enamel Primer.  Spray cans for large areas & convenience, and airbrush for smaller, more intricate parts where I don't want too much paint build-up.

I'll use Testors flat white enamel as a primer or undercoat for areas that are going to have lighter finish color, like white, yellow or red.

Mark