I was hot and heavy into the MSA discs a few months ago. I've had nothing since. It wasn't due to a burn out or a lack of interest. It was a lack of product. The only discs missing from my collection are the ones that are rarely listed anywhere and are nearly impossible to find.
I have several saved eBay searches for the missing discs and I got a hit a couple weeks ago. A 1979 Wiffle Manny Trillo was listed. It was priced reasonably and I hit the BIN.