Drypoint techniqe can be used with plexi, aluminum, copper or any other metal used as a plate. You are correct in how it is inked and then wiped off to leave ink only in the etched areas.
There really are only two or three techniques that you can do in printmaking that does not required a press; lino and wood cut, and in some instances mono prints, but they are difficult.
Check with Dick Blick for presses. You can get one at a great price through them.
Ah, make the most of what we yet may spend, before we too into the dust descend.... Omar Khayyam
Stone Chief Studio