When you buy a car you pay extra for the cool stuff that it does. You're also paying for its high status in society. Its the same with vbulletin. Its the best, and guys like me often only join forum that use it. I probably wouldnt use DP as much if they didnt use vbulletin. $160 is a lifetime lisence. its only $85 a year.....
Haven’t yet seen a free alternative that is as good as vBulletin, but if you can make one and provide it for free, then hats off to you. In fact if you manage to do that, your script would become the wordpress of forum land
It is not an easy task to build a full features forum script. it took VB and IPB years of development and a staff team to build the current piece of software you get for a small fee of 160$ Look at PHPbb. although they are working hard on it. it is yet young to compete with VB and IPB to build that large software you need ideas and brains. one is not enough. they built they software upon thousands of user feedbacks and suggestions. Not putting out your glow but just making you realize that it won't be an easy task. but with it open source you can build a large community and get some contributions (in terms of programming not money) Good luck