Several months ago I transitioned all my cards from "Cardsavers" to mylar sleeves. I met the owner of
http://tcverify.com at a card show and he gave me a free sample of these mylar sleeves he was producing. I ordered from him twice and was very happy. It's been six months since I ordered from him, but last I heard he was producing mylar sleeves sized for T-206 cards.
If you email or call him I bet he would send you a sample.
Larry