First, please read
my reply to your other thread. The price: $160 USD.
The second question regarding the comparison between open source products vs vB, a commercial product, really depends on your needs. I can't answer that for you. I can tell you, however, that vB is very flexible, has tremendous official and non-official support, is web-server friendly and is user-friendly. I say "user-friendly" because the owner's side of it can be overwhelming. If you're willing to dab into vB's routines unrestricted then you'll find that vB is an awesome product.