[Carlos]

Well, it depends on what industry you want to tackle. Right now, the multimedia industry is making money from ads (and I mean company-issued ads), smaller sites make money from google/yahoo adsense/ads. Other companies make money from services, and product promotion. There are sites who design backends for those merchandise sales sites. That would cost you a lot because they charge thousands JUST for coding the backend/frontend AND the mainpages themselves.

So, yea, it depends on what you're doing.