I am learning that the gun needs to be 1986 and older to be bought by an individual like me.
Yup, but you don't have to worry too much about that. The guns your SOT 03 dealer has to sell to you -- or that he can transfer in to sell to you -- are all going to be pre-86 "Transferable."
If I was looking to make this jump, I'd probably go for the Mac series as well, and save up for whatever Lage bits and pieces tickled my fancy.
There are some issues with a large number of those guns, but if you do some research on what you're getting and what it might need to be made durable/reliable, you could do all right.
The Lage parts are really what sell the idea to me. (As a stand-alone item... not so much.) The ability to make it almost any flavor of 9mm sub-gun you want is pretty appealing. 'Course, those aren't cheap parts, either.
For a bit more money Uzis are solid guns with an extensive community of fans and suppliers to help you keep the good times rollin'.
I don't think of any assault rifle as "cheap" to play with, considering the ammo is going to be something near $0.50 a shot. The ACC556s are probably the most ... responsible(?) ... choice as TR said.
About 5 years back a dealer pal of mine had a pair of FNCs that made me drool a lot. REALLY wanted one, but $9,000 was more than I could find in the couch cushions. And then he got nailed for "creatively repairing" MACs into more expensive MGs so I'm kind of glad I didn't buy anything from him.