If you don't go DIY, I predict that after substantial research you'll push your budget up a bit and go for a Rythmik FV15HP. I say that because that's what I ended up doing, and I don't think I'm alone there, this sub seems to be the current AVS darling in the $1-$2K price range. Which is not to say that there aren't lots of other good choices out there (and unlike many others on here, I have no experience with most of the alternatives).
Benq W1070 projector w/ Chief RSM mount with custom interface bracket
119" Da-Lite Cinema Contour with High-Contrast (gray) Da-Mat screen
Denon X2000 receiver fed by Panasonic DMP-BDT210 Bluray player
Focal Chorus 700-series towers and center, JMLab Tantal 500-series bookshelf rears
Rythmik FV15HP sub