I am working on a kind of a social network. We have few hundred users who use our site and have a hosting for around 250$. Its enough for the beggining, but we are expanding and we are awaiting a lot of new users soon. I am curious and it would be very helpful if some could give a feedback, how can the price for hosting raise according to number of users, how high can it be for 5 000 users or 10 000...
I know there are also other things that influence the cost, but maybe some tips or thoughts, some experience would be great.
It depends upon what script you use. Check out this thread http://www.webhostingtalk.com/showthread.php?t=1050702
It might be helpful as it was lots better for me. I have 2 site hosted in this server using Social Engine 4 and I charge $50/mo each. Sites load fast and each of them have about 5k users.