Yes, the software cost $140 for an owners license. I say owners, because once you own it, it's yours. The first year comes with free updates. Support here is always free via ticket support and we also have a very friendly and active community. For every year there after, it is only $40 to renew. So if you do not pay the renew fee today and allowed it to expire, it would still be $40 when you do decide to renew (and if you didn't renew, you would still own the software and could still use it)
YES, there is both a vBulletin 3 and a vBulletin 4 importer. The vBulletin 4 importer can be found here
Both importers are easy to use and fun very smoothly. They're designed so that even a noob (not saying you are one) could easily convert to XenForo. But if you want help to do so, there are a lot of willing people here who can either guide you through it or do it for you (myself included)
I just wanted to say that in my experience, the ... -> XF converters have worked like the rest of their software: effortlessly, and without a bug. The link to the vb4->XF converter has been posted. Let us know if we can help with anything.