I don’t want to go into whether buying/selling links is good or bad but I can say that Textlinkbrokers are one of the top link brokers out there. However, the link brokers inventory in the gambling industry is poor so you will end up with low quality sites linking to you or in your case you linking to them.
Does Google know about their inventory? I would think that they have accounts on the biggest brokers out there.
/babyface