Social network- Best route?

Hi, everyone

Ive been browsing the forums here for a few hours and couldn't find the answer to my question, so please forgive me if I'm rehashing an old topic
Also apologies if it's in the wrong section....

Im looking to start a social network site, and need a little help as im not a programmer..
The site is going to need all of the usual social networking features-

User profiles / add friends
upload photos
upload videos
rate photos (plus a top ten of highest rated photos)
send private messages
user blog
create groups
forum
invite from hotmail/yahoo/google address books
digg style section where users can submit links and vote them up/down

Could this be made using phpizabi? if so any ideas how much it would cost and how long it would take to get a freelancer to customize it......... Does anyone have any other suggestions on how it could be done? Could it be done fairly cheaply using joomla? I also have another few features the site would need, but ive been told by a programmer friend that they are pretty simple..

One of the main considerations would be cost. I need to get it done as cheaply as possible, no more than a few thousand dollars.

Thanks in advance
Maj