You could always try videofitness.com. There is an exchange forum. Where you trade tapes with other folks. I've gotton a few of my older Cathe tapes this way.
Another place is the Ya Ya swapmeet. You need to register, but registration is free. If you click on "Links" on the top of any Cathe forum page, you'll see the link (The Firm Ya Ya's).
Try eBay on a regular basis. I think a couple of earlier ones have been posted recently. The other sources mentioned above are good as well. If you have a good seller and you pay promptly, you can get them fairly quickly.
