We can't tell you because of different factors such as skin,graphics, etc. You have to keep an eye on you current host to see how much it uses in a month, thats the only way to accurately tell how much is needed.

Wow there's some annoying spammers out there above my post.

Anyways...
There's no way for you to estimate that. Do you know exactly how many visitors you will have and how much information they're going to access? Then you won't have a clue.

My advice would be to get a cheap shared hosting plan that has unlimited bandwidth and monitor your site to get a real idea of how much you are using and will need as you expand your site. I'm sure you can get something cheap from GoDaddy like others have been saying.

Valdeam

thank you for that thread