Check out the Bower's Board for more info on current prices. Original Powder Springs/RPB MACs are usually the more valuable, the later SWD M11/9s are pretty common. You can get a New In Box (NIB) M11/9 for under $1000 right now.
www.subguns.com
You'll need to check on whether or not you can get a CLEO signoff on your Form 4 for both the suppressor and SMG, and it's $200 per transfer - that's $400 over and above whatever the cost of the MAC and can are.
Good luck