Anyone have any advice on what to look for, specifications it should have or a certain brand. I'd like to buy one and don't know the first thing about what is good and what isn't. Thanks.

I purchased a Badger Anthem 155 from Michael's (and I had a 1/2 off coupon) which made the airbrush $50 after my discount. It works great. I use it only for food grade though. It connects to a small pancake compressor that I purchased from Walmart for around $30. You only need a compressor that is able to go to 100 psi. The compressor is louder and larger than those you see on cake websites but it is also much less expensive. If you don't have a Michael's you might find this airbrush in other arts and crafts stores. It retails normally at around $99. hth

I know this an older post but I just bought one.. delivered yesterday actually.. off of ebay...
http://cgi.ebay.com/Super-Deluxe-CAKE-DECORATING-AIRBRUSH-KIT-w-Compressor_W0QQitemZ200377357400QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item2ea76bd458&_trksid=p3286.c0.m14
there's the link.. it's only $109 & it comes w/12 Americolor bottles of color. Not sure how to put it together or use it yet, but guess I'll figure it out.. )

crazycakes, this is the exact one I'm planning on ordering today!!! how is it?

well i don't know how to use it yet but it's nice. i got it via fedex w/in about 5 or 6 days. amazon has the same one for $140.. i'm glad i checked ebay first! the only thing i was disappointed about was the fact that it didn't come w/instructions on how to put it together. it literally says connect the hoses, plug in the power supply & turn it on.. haha! oh well... i guess that's what the internet is for!!
if you know of any good tutorials on how to airbrush lemme know..