How much would it cost to pay someone to create a user management system that could let users send PM's, have avatars, and have some sort of point system?

ummm theres no need to pay there is http://joomla.org with a forum and comminity builder plugin in get;s all that done for free (joomla is also opensource so you could remove links back to their site)

ah i see, thank you

but i still want to know how much it would cost

Couldnt say exactly how much it would cost as I dont know anything about building them however I would imagine it would be a hell of alot.