Check all the forums' Buy/Sell sections and you'll find people selling lists. But keep in mind that even if only a dozen Scrapebox users buy the same list, every single URL in that previously-valuable list will be absolutely raped (i.e. spammed to death).
The links may still have value and count for something but it's much better just to scrape your own lists. I mean, that's one of the main features of SB so why not use it instead of getting someone else's list? There are thousands upon thousands of blogs out there that no one has commented on, you just have to find them. It's not terribly difficult to do.