Website designed with unique features

I have several requests for the site I'm trying to build, firstly it will be mostly a social media website (nothing nearly as complex as fb/myspace etc., but some similar aspects).

One of the unique things that we want there to be a "battling" element to the site, where a user uploads photos that he/she names and that are tied to his/her account and those photos are randomly matched against other photos from other users, and then voted on by other users. An example of the battling element is this website: http://puppywar.com/ (though I don't know if the puppies are tied to specific user accounts). We would also want users to accrue points based on the battles they won which would be tied to their account as well.

Also, as a separate feature, I'm wanting to have a marketplace where people could buy/sell/trade the photos with one another using those points.

Some more features this would involve are a blog, friends list, private messaging, and profile pages. None of which are expected to be nearly as in detail or advanced as fb or myspace as I said.

I know this is a fairly vague description, but I think its probably enough info to say how hard it would be/how much it may cost.