Those are really cool! I'd never pay $40, but honestly, there isn't much I would pay that much for because I'd try to make it myself instead! I bet there is a market for it though!! What a great idea!
Here is another link I found for the bracelet cuff blanks. http://www.beadwork-supplies.com/aluminumblanks.html
They have a retail side & wholesale too, although you have to purchase 4 gross for wholesale. http://www.beadwork-supplies.com/wholesale.html
It looks like a cool site, and I think their prices seem good too. I'm always a little apprehensive about a website as opposed to ebay or etsy shop until I try them out, but it looks like you pay through Paypal, so for me, I'd be okay with it.
OK... just noticed that this website is the same people as in the etsy shop link posted above my post. (duh, should have noticed I guess.)