The problem is in NH nobody is gonna sell the cripplemags, unless you're not concerned about that issue. I've seen the normal mags for M&Ps from time to time at the shows.
The cripples always seem to be hard to come by, in MA or otherwise.
I have 4 of them you can use them if you are going to the Steel Challenge on November 5. I'll be shooting another gun.
If you are going to Harvard and need them let me know and I'll bring the 9mm with me. They fit the M&P9c, don't know if they are what you need, but you are welcome to borrow them.