I think the place that makes the highest quality stuff is out of Chicago. I think it's this place
http://horween.com/ You might be able to buy a sheet from them, but get your wallet out, it's PRICEY stuff. In fact I think they have all their stuff allocated or something like that. They sell it to these places all over the world that use it to make those shoes that cost $1,000 per pair. Italian shoes and such....purses too.
Surely they would have end pieces that weren't up to their specs that they could sell you.
One thing I can tell you is that not all cordovan leather is the same. I've got some on an Eagles Flight Archery tab and it's great stuff. Really stiff and durable and would last for decades...I'm sure of that.
A while back a member on here sold me a sheet of cordovan that he got from a local leather shop out west or something. It is cordovan, but it's NOT the stuff like the place I posted would sell for those expensive bags and shoes.
Maybe you could go raid the closet of your wife and see what you could come up with. You might be surprised. You'd end up with a few really sweet tabs and probably a nice pop knot or 2 from a frying pan.
Good luck in your search and let us know how you make out.
Nalajr