I run a forum at the moment which transfers around 20gb in bandwidth a month but always growing. I have two hosts in mind, they are with Sectorlink and Hostrocket. I'm open to any other suggestions though, in that price range - would prefer to only pay upto $30 a month. Has to be very reliable.
Call the companies you're looking at up and ask questions. See how responsive they are. Do it several times even if you ask the same things or if you ask questions you already know the answers to. By doing this, you'll get a feel for the company and how responsive they generally are.