Their webspace to bandwidth ratio is 1:3, which is kind of lopsided. Do a search on onefusion for more info. I have 2 reseller accounts with Voxtreme and MercuryHost, and I've been very satisfied. Check them out.
Well, unlike Plesk, CPanel allows you to oversell your space and bandwith. (Right now I am stuck with Plesk). 30 GB should be plenty to use, and if not, either purchase an upgrade, or go somewhere else .