For like 4k you can get an STi block with foged pistons. :-/
But you gotta remember, the subie dealer is charging you retail price. They're going to charge you a huge markup for anything they order, including that motor. And dealership labor is always high.
If I were you I'd find a local, highly rated performance shop and go to them. they'll help you find a new block and the labor will at worst be the same.
You can probably do a pretty moderate STi build for what your Subie dealer is charging you.