Thinning paint

The pricetag.

True that.

Depending on what paint you are using, there are many hardware store alternatives.  One thing that may affect the price of name brand hobby paints is a higher quality control, but I haven't found any real difference in generic vs name brand.

Reid

Apart from the obvious price difference, quite a few airbrush/model paint specific thinners have retarders in them to prevent tip dry & help give a smoother finish, they are often less harsh than generic thinners . 

OK here's an example

paint tamiya

thinner - rubbing alcohol/methylated spirits, nice result, dries very fast, may in fact dry on way to model producing a grainy effect (rare but have seen it).

thinner - Tamiya X-20A thinner, nice result, takes a little longer to dry may need to be careful while airbrusing as you end up touching wet areas

thinner - water- ok results, need to be careful as it takes sometime to dry and you get paint runs.

I used to be fan of Testors airbrush thinner.  I used it only for the actual thinning of paint in the airbrush, not for cleanup.  The cost of the thinner to do a kit was negligible compared to the price of the kit and other things like the PE and other accessories.  I felt there was some difference compared to hardware store thinners.

Testors airbrush thinner has been very hard to find lately.  Don't know if they are discontinuing it or not.  So, I had to experiment, and found that the difference seemed to be that I had to increase the thinner amount a little when using hardware store thinner.  So I will now be using the hardware store stuff- not for cost reasons- again, the amount of thinner used in airbrushing doesn't cost that much, but of necessity.

One big caveat, however.  Be careful which hardware store "thinner" you buy.  There are cheap thinners sold these days that are milky white rather than clear.  These have a lot of crud in them.  I hold out for real "mineral spirits" or turpentine, rather than something just labeled paint thinner.  These two specific solvents are more expensive than the generic paint thinner, so I am probably not saving any money compared to the cost of the old Testors Airbrush Thinner.

Also, I have committed myself to learning how to use acrylics. I can see the handwriting on the wall- solvent-based paints are disappearing :-(    I frequently do subjects that require glossy finishes, which I find a real challenge with acrylics.

I like to use Hawkeye Hobbies thinner just for thinning and washes,it's a bigger can and it goes along way.I use the hardware store stuff for cleanup

Since I use enamels almost exclusively (Testors, Testors Model Master, Humbrol and a couple three bottles of Pactra paints) I quit using OEM thinners years ago - now I use DuPont 3812S Fast Dry Enamel Reducer for thinning and a lacquer thinner which is available at Wally World, either of the lumber yards in town or either of the hardware stores in town for clean up.  I've been very happy with the results these products give me, even if I do admit I changed to save money. (Some people might say that that's stupid, but as one of Murphy's Rules of Combat states: "If it's stupid but works, then it ain't stupid!")