Noise is right. There are too many variables. Perhaps what you are looking for is a rough idea of the steps you're going to get into. Here goes:
Hosting: Anywhere from $10 monthly to $500 monthly and up, depending on whether you're on a dedicated server, shared server, what type of server, how much bandwidth is in your package, whether it is managed or not, etc. Make sure they allow adult material even if your material is only soft-R or whatever.
Programming: Somebody is going to have to program you a site. They (or you) could start with a content management system which is free, but it can still take a while to customize it how you want it. From scratch, a fully-programmed site could cost well into the 10's of thousands. I guess if your programmer starts from a turnkey platform, it should cost maybe in the hundreds.
Design: Almost no programmers out there are good graphic designers, and vice versa (IMO). You've either got to get two people together to program and design your site, or get a company that has these people in-house, or find someone that can do both.
Billing: If you go with a 3rd-party processor like CCbill, expect to pay them 15% to 20% in fees. If you want to go through the excruciating task of setting up your own merchant account and 1st-party credit card processor, well, good luck. You basically can't get one in America, but you can get companies that will set you one up offshore for hefty fees. If you do, they'll charge a lower percentage, but expect up-front fees into the thousands, rolling reserves, and lord knows what other fees.
If you want to avoid all that, then of course I recommend using one of the various clip store services that are around.

Stay messy, my friends.