I seem to remember paying not as much for them but that was several months ago. bobsag3 said in a previous post that they've got around 50 they can sell for $45 plus shipping. I've not been able to get good word back from my usual PSU source about how many we can get ahold of to stock, or what prices look like.
These PSUs could still support 5 if they're right at or under 500W, but for safety (and marginally improved efficiency) it would probably be better to run 4 per. 50 would then require 13, or 12 if you did some clever load-balancing. At that range, you're in the second-tier price break of $57 per board. 160 cables would be $560 to $720 depending if you wanted 18" or 36" or a mix of both.
We're in preorder stage now for the boards; PCBs are expected to arrive about the 22nd and we'll have the rest of parts by then to start manufacture for shipping by the 25th. If you get in the queue right now, we'll probably be shipping your boards and cables on or before the 28th.
If you're interested in a purchase or want to discuss further, email
sales@gekkoscience.com and we'll get you set up.