A friend of mine started a free forum and he ran it for about 5 months, slowly getting members. I told him I had space on my VPS, so he bought the database backup from the free forum, and it is now hosted on my server (in which I inherited an Admin position). It gained in popularity significantly, as we are almost at 50,000 posts, with about 7 months of being online. We are in the process of expanding it and getting some real juicy content up.
if you can avoid the freeforum, that's great, but if you have decent activity on a free forum, GET YOUR OWN HOSTING, buy that DB backup. It is truly worth it.