Small room....treating 1st reflection points

1" foam/treatment will work to some degree, in particular with higher frequencies as noted, just not as much as equivalent 2" foam product.

No way to know what will "sound best" without trying.

I like the "lego" approach with wall treatments. Start with smaller measured amounts of treatment, like 2'X2'X1". Add more or less as needed until best results achieved at primary listening location(s).

So what's a good place to buy prefab treatment products without breaking the bank?

Rebbi, GIK makes nice and affordable ones. I use Vicoustic personally.

So what's a good place to buy prefab treatment products without breaking the bank?
Rebbi

If you need foam products I recommend http://nextacoustics.com/.

For acoustic panels I have used http://www.atsacoustics.com/ with great success. They made me a custom size panel at a very reasonable price.

A super cheap way to try if you hear a difference is to simply place pillows on the first reflection points...except ceiling, of course.

I built my DIY traps with fiberglass panels and they work fine for me. Maybe commercial ones would be better, but the physics behind what's going on is pretty basic, especially at the high frequencies these can treat, so I tend to think DIY gets you very close to "there".

Using REW I could not measure any impact on low frequencies by using these or DIY tube traps (ok, a marginal improvement with the latter that was not worth the looks), but did notice a clear impact from using a Helmholtz resonator (at the design frequency, of course).