Are there any commercially available devices to make your own gas checks except the Freechex II that the guy out of CA sells? It seems a little fishy to me when the guy says he's making them but won't set a price, just lets it go to highest bidder. I mean he knows how much material and labor he has in it.

You might check with "Corbin", the guys that make Bullet Forming Dies and Presses. Memory is not what it used to be, but I seem to remember them offering the tools to make Gas Checks. May have used Aluminum Soda Pop Cans for the material.

But, that could be totally wrong.
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If you are shooting Straight Wall cartridges, you can also make Milk Carton(waxed cardboard), Toothpaste Box(cardboard), or Meat Tray(styrofoam) Gas Checks. Drill out a Primer Pocket on a Case that has been shot but not resized. Champfer the inside of the Case Mouth and use that Case as a Cutter. Lay the material of your choice on some wood and hammer the Gas Checks out. Push something through the Primer Pocket to get them out of the Case.

They work pretty well to protect the Bullet Base from Gas Cutting on a Plain Base(not designed for a Gas Check, nor Hollow Base) Lead Bullet.

Best of luck to you.

Corbin still does make the die set. They work quite well. Here is the link:
Corbin Gas Check

At $500 for the dies not counting the copper strip material and time I could buy a heck of a lot of gas checks at $25-30/1000.

Take a look over on the "Cast Boolit" site, there is a poster "Pat Marlin" who has been working on a gas check maker to sell and I believe he may have some ready now.