OK just an idee i'm playing with.
What is you hace about 100 credits for every MB of space you want you pay 1 credit. For 1GB bandwidth you pay also 1 credit. For CGI, you pay 10credits, For MySQL you also pay 10 credits. No ads 100 credits. And so on. Good idee?
At that way people can choose what they want. If you don't need CGI or PHP, you don't ask for it and you can get more space. If you need mutch banwidth you just cut in the space.
BTW that 100 credits are free. And you can buy more if you want (4$ for 100).