There are many pre-86 in the market, but they are in the rnage of $4500+. There are basically two types of full-auto 10/22's: open-bolt and close-bolt. Close-bolt shoots "cleaner" than the open version. Neither is a simple "drop-in trigger group". Due to the design of basic 10/22, most of 10/22 need extensive modification for both the trigger group and bolt.
Also, most of the full auto 10/22 are pretty fast (~1000+ rpm, but who cares! 22 ammo is cheap!
). Norvell (sp?) makes one that you can adjust the cyclic rate and it's a close-bolt design. Go to some C-3 boards and/or ask your local C-3 dealers for more info.