whats the most expensive (largest & highest PR) link building network?

I'm wondering who provides the high teir of backlinking? ie largest and most expensive backlink service?

I'm talking about a company that offers, say, 500 back links or 1000 backlinks from PR5-8 sites for a monthly fee.

thx for your insight.

@crwth there are plenty of them here on BHW! Check the BST thread. Personally I've tested d3t0x's services and his network was awesome!