Ah, I should have read the text and not just your subject line. That's a good price, then: 4 kits for the price of 2. The tea towel kit's pretty cool if you want to sound like Ringo. Just add some crushing compression. I didn't care for the Ossifar kit, though.
I have several of the Wavesfactory libraries, all decent-sounding, and the Rock Kit in particular sounds great. But if you're into Kontakt-based drum kits,
Drumwerks offers excellent full kits for $8 to $15 ($25 for all 6 kits) plus individual drums for $3 to $5 so you can mix 'n match.