Where to get a really great wash/filter set?

Look in online places like Squadron, MegaHobby, Scalehobbyist etc...

Why not make your own with artists oils and thinner? You can get an oil paint set from Hobby Lobby with a 40% coupon for $15 to $25 and you can make tons of washes and filters.

I was using the generic thinner from Home Depot but have noticed that it doesn't produce an even mixture. I have sitched to the red Testors thinner can from Hobby Lobby which produces an even mixture. 

Ebay shops and Amazon

I second Plasticjunkie, just make your own.

I use mineral spirits with oils.  I also use acrylics for washes, and in that case, I use craft store paints, mostly, and water.  It takes a little practice, but you can get good at making your own.

I do concede that buying ready-made washes takes the guesswork out of it.  But goes against my Dutchy senses.

If you're not comfortable making your own (don't feel bad, I'm not comfortable with doing that at my skill level), check out Hobbylinc. Almost everything I've looked at there is cheaper than the craft/hobby stores and amazon. They seem to be a relatively small operation, so it will take a day or so for them to get your order shipped, but, if you're not pressed for time, I have been getting my paints and such from them for half of what they cost at hobby lobby. 

I like the washes from Phil Flory.  They are clay-based and really quite easy to work with.  One caveat however;  DO NOT contaminate these washes with any solvent.   Don't use the same stirring sticks, mixing cups, brushes, etc.  It will ruin the wash.  Other than that, I think they are fool-proof.  Read more about them here:

http://www.florymodels.co.uk/washes/

Gary

I haven't built a kit in 10 years (though i started one last night!!), but back then there were no pre-mixed washes and such. Then, I mixed my stuff just like the guys above, with artist oils and thinner. I mopped the "sludge" all over my aircraft, usually in dark grey, and let it dry over night. Oils dry slowly. The next day I would take a scrap of T-shirt and dip it into the thinner and begin wiping in the direction of the air flow. I turned out great evertime. Let that dry for another 24 hours and there you have it. Cheap, easy, and a tube of oil lasts a long time for $5.