I got my black '85 Targa on Bring a Trailer in August, and shortly afterward got a nicely matted and framed copy of the Maxell magazine ad from
https://www.secondmoonshot.com. FYI they do great work and will do custom orders too.
But, I still wanted the much nicer Weaver Gallery version--and surprisingly found one on Facebook Marketplace just a couple days ago. Quite reasonably priced, and "only" 3 hours away.
The frame was a bit catawampus and the glass (actually plexiglass) needed cleaning on both sides, so once I got it home I carefully disassembled, cleaned, and reassembled everything. It's not perfect, but it's pretty good!
These posters are still out there to be found if you are patient.