Helm- http://www.webhostautomation.com includes built-in billing software so you may want to look for a host that offers this controlpanel. Note: Helm runs on Windows only, I wasn't sure if you wanted Linux or Windows based hosting.
mmm I think 5gigs would be too small.Even buying for myself for just a website I didnt buy 5gigs.
5GB's is plenty, especially if you're just starting out. It will take quite a bit of time for you to fill that up. You should also look at lower packages and choose a provider with a good upgrade path. Why pay for resources you won't even use until months later?
I would suggest looking around the offers section to see what is out there. Get a list a providers and search for reviews on them. Your budget sounds like its pretty much right on target for your request.
A VPS would probably be a waste of money if you are just starting out. A good reliable company offering a mid sized Reseller with room to grow as you do would be great for you. You may want to confide in google.com and wht
I don't use either (I Use VPS at Knownhost) but I have seen good reviews from all here at WHT just do a search and read up on a company that you are interested in. Take a look in the offers section as well located here If you see a particular special that you like search on that company as well. WHT has a wealth of information on many hosting companies.
Good luck in your search and do take your time and research as much as you can, you won't regret it.