If you are a MA resident, and not a LEO, then in MA you can only buy used Glocks manufactured before (I think) November 1998, AND (again I think) Glocks that have been documented to have been in the state prior to that date. Same rules apply for interstate transfers via FFL. There are lots of Gen2 Glocks available at dealers but they run a lot higher than everywhere else - typically $500 for a used G17/19/22. 23's are a little rare - run $575-$600, and 26/27's run $7-800. I think a non-resident moving to the state can bring with them any vintage Glock - but you must immediately apply for a resident permit, and register the gun. You can get a non-resident permit and bring any vintage Glock into the state.