Thanks a lot for your answers guys.
I've never been into bicycles before. I used to ride my longskates for every trip, but long story made short I changed house and now I'm about 5 miles away from downtown with some pretty steep hills along the way.
While It's no San Francisco a single speed would probably not be versatile enough..
I'd like to build my bike by myself, so the price difference is not really an issue as I can spread the cost over a few months.
The new (well, to me at least) carbon gates' belt system seems to be quite resistant to belt stretching based on what I've read. The low-maintenance grease-free argument sounds good to me too...
Now, do you think that it would be possible for me (a complete noob) to build a good belt driven bicycle for (much) less than 1000$?