Where are the major players buying their backlinks?

Hi, I've been looking at sites ranking for very hard keywords, and it seems to me that most of them are buying links from homepages of what seem to be made for backlink websites. I was really curious if there are good places to buy homepage backlinks, and what the rate is. All the rank building websites seem to have their own 200-700 spam links back to them, so what's the going rate for one of these links? - just trying to learn the market

The wholesale price of freshly verified backlinks with anchor text is about $5 per 10,000 unique domains. Retail for that seems to be around $15 to $20.

That sounds really reasonable compared to other rates I've seen, can you point me to a source with these rates?