There are any number of ways to obtain a set. Most of us just haunt gun shows seeking a set of nasty grips to harvest the medallions. Its not as hopeless as some make it sound. I've been collecting them for a while now with the goal being to make a set of buttons. Then I'll have my wife sew them on a Woolrich chamois shirt to wear to gun shows.
yes, I've got a few loose ones.
A while back one of the grip makers went to the time and expense of having a die made to strike them. His efforts and money was rewarded by S&W's legal department writing a letter. Rumor has it the ones struck in Sterling were $150 a pair, with the identical item struck in 14k gold significantly worse. In fact, the die that was carved was made from a less than perfect original. Its amusing to note that I somehow have both the original with a minor imperfection, and a set or two of the silver ones with the same imperfection. Strange how that works.