AAS Ultra-Analog. Got it for $15. It has some good sounds, but I thought the GUI was way to small. I also can't imagine anyone ever having spent the list of $199 on it.
Steven Slate Drums for Kontakt 3. They are actually quite good for a late 80s/90s big hard rock drum sound. I think I found them awkward to work with if you want to audition different kits.
Dan Dean Basses. Another of the classic $15 no brainers from audiomidi. I think I got it for their Rickenbackers, but now that I have the NI Rickenbacker, it does not see that much use. I don't recall being that impressed with the Fenders, but there was perhaps a Guild or Firebird in there which sounded good enough when run through a bass amp sim.
EZ Keys Upright. $29 Black Friday last year. The upright piano sound is okay, but the whole reason I got that was for the MIDI arranger.
As for the AAS String Studio, I regretted missing the no-brainer but ended up getting that based off the Journeys and Entangled Species sets which I got as freebies. And that it came with the bundle which was on sale at JRR.