To get someone to develop a forum for you, may I assure is most likly 10x the price of a full owned liscense.
Anyways, I have been analysing the age gorups, type of site, dedication of many of the members both here and at the official site.
vBulletin targets more long-term based, mature, dedicated audience it seems, well the majority of the time. vBulletin is made to give a proffesional look, at the same time give you all and more of the features you get/don't get else where.
Most of all the 'legit' boards are all dedicated, and have proffesional appeal to them. Then there are all the pirated boards where you see the difference. For them, freeboards are made in majority, these sites are temporary, don't want to invest into there site to make it grow, but just want to start a site for the heck of it.
I can go on, but I know in general many get this point, though it may not be the main point.
Now to convince, I am a phpBB user, well was, and when I got the power of vB under my belt, the possibilities were endless, the coding is secure, and clean, I am able to make all possible modifications I need, when I want to and when I need to. The Template System is geniously coded, if you see other board software, they are individual files, and are usually needed to be downloaded to be edited, vB packages this all in a nice template system, which I love. I am hooked on vB, love the hacks, love the support, love vB.org and plan to dedicate a nice amount of time here.
Also if you are not sure what you want, test, and even if you want start off with a free board, there are plenty converters available, and I have seen many sites that start off with free board and convert to vB.
OK enough typing for me