how much would building a customdesigned forum cost?

i am thinking about letting someone build a custom forum for one of my sites.

I would like to add a lot of functions which are not available for the forum software available.

what do you guys think it would cost me to hire a programmer to build a forum from scratch?

Also how many hours do you think it will cost the programmer?

well your looking anywhere from 20-30 a hour at least for most custom programming, setting up the forum is the easy part but depending what you want is then can be calculated. could be 10 hours could be 40 hours. When investing into web sites you need to be prepared for a instant turn over.

Have you got any experience in web hosting forums or questions about the process?

The work for something like this would be measured in weeks, not hours. Your question is far too open-ended, however, for any kind of estimate to be made for this kind of work. "I want a product that does different things than other products" isn't much to go on.

What kind of features are you looking for that aren't available in commercial or open source forum software?