I'm relatively new to the Rev2 myself, and I haven't actively sought out patch banks, but I'll bite:
Can you give us a better idea of what you mean by "classic"? To me a "classic" analog synth sound is something in the Wendy Carlos/Jean Michel Jarre/Tomita/Vangelis vein, but you might have a totally different thing in mind.
Yes, you nailed it. Also, classic Prophet 5 sounds since this is its legacy. I like musically useful presets. Not sound effect patches. Not the music was written for me with a sequencer and I hold one key patches. Just a good variety of sounds to write music with. The Prophet 12 set nailed it with quality and variety. I don't like all of them, but I like quite a few.
Have you tried tweaking the presets to get them closer to what you want? The Rev2 has two sequencers and an arpeggiator, so yes the built-ins demonstrate those a lot. They're also easy to disable if the base tone is appealing to you. (Editing will also give you an appreciation for the effort needed to get a single patch just right, so maybe that $40 bank of 128 will seem like a deal.) I personally enjoy sound design nearly as much as composing or performing, so I fully expected to be tweaking presets at a minimum when I bought the Rev2.
I'm not interested in sound design, and never have been. Sure, I can and do tweak sounds to taste all the time. Sadly, with the way my studio is set up, I can't sit in front of the unit and play at the same time. I'd have to buy an editor to do that. Also, a patch doesn't have to be overly complex to be good either.
My guess is that the $20 patch bank, if you find it, will contain fewer than half as many good programs as the $40 bank.
I wouldn't count on that. Price does not equal and has never equaled quality, it's just a price. I've bought and/or reviewed plenty of sound sets that are fantastic even in the last few years that are in the under $20 range that sound great. I've also gotten some duds too. It would be nice if it was possible to play a $40 set to see if one even likes it, but obviously that's not possible. There are certain sound designers that I know do a fantastic job (Howard Scarr, Brok Landers of Big Tone, Rob Papen, etc.) I know what to expect from these guys. The 2 soundbanks by Two Quiet Suns for the Evolver was fantastic (and made my keep the Evolver). However I know there are plenty of guys who like to 'experiment' and make weird noises. Ya, not my thing. There are plenty of so-so to not so good amateur sound designers too. Obviously this is all my opinion. Thankfully there are sound demos to get somewhat of an idea for most banks these days. It's not 1995 anymore! Woohoo! But I don't like blowing a lot of money on something if I don't know if I'm going to like it. Then there are the free banks, and some of those are better than the paid for banks....
Devon