Just cruising through different dealers ads and NFA specific ads today I've seen M10's at $2750, and M11/9's in the same range. Add $200 tax stamp and whatever your dealer charges to do the transfer, plus any fees that your local law enforcement may charge (NICS check, fingerprint charges, etc.).
If you look just a little bit you should be able to get the whole thing done for $3000. Of course, you'll probably want a Lage slowfire kit for it, and some sort of different stock, and lots of mags.... All that adds up dollars quickly to the total also