Not only has retail sale been illegal, the manufacture of the machine gun itself is also illegal unless you have a 07 FFL and a 02 SOT. IIRC manufacturing a machine gun under a 07/02 does not require a demo letter from local LEOs. Illegally manufacturing any NFA weapon (including a machine gun) holds a penalty of 10 years in federal prison. Not something to just do on a whim.
If you really want a FA Glock 17, there's a chance that there might be a few in the registry (though I don't think any Glock 18s were imported before the '86 ban). They'll probably run you something in the tens of thousands of dollars, and still require transfer paperwork which will take about 6 months.
Don't do it illegally. A toy is not worth loosing your job, 10 years in federal prison, and then having a hell of a time trying to find a job afterwards with a felony conviction on your record.