Diamond hone set; up to 6k grit?

I've been looking around for a cheap (<£40) set of hones and a razor to play around with. I read the various guides on the wiki and saw that I should get a 1k, 4k, and 8k grit at minimum to be able to hone effectively. Anyway I spotted this on eBay, but as I understand it diamond hones only really go up to about 1k in grit, is that right? If so, are the grits listed here (300, 1.5k, 6k) based on some other scale? Are they possibly just an outright lie?

I don't think you will get the shave you want that way. To harsh and not high in grit enough. 40 is not going to get you there I'm afraid. I'd use that money to send off a razor to hone for you.
Paul