You think it will take more than 650 hours to build that?

Seems like 40-80 hours to me. After you find some well-written PHP forum software that already uses PostgreSQL, you just need to add the dozen or so major required features and then some minor required features that will probably take less than an hour each on average.

The forum will probably have at least 100 more BTC by the time I start thinking about ending bidding.