Stamp and other size mounts

I sometimes restock my supply whenever I happen on a Barnes and Noble or Borders--both usually have a good range.

Other than that, there is a nice little collectibles "Mom and Pop" in Memphis, and I call "Pop the Philatelist" up whenever I need Showgards. He asks me which stamp I have and then tells me what I need and sends it to me. For the life of me, I can't rememember his name or the name of the store.

If you haven't found a better source by then, tomorrow I will get it out of my roladex and post it.
Any local stamp or coin shop will have any size you need. They sell them almost as cheaply as most wholesale sources considering the quantity you will most likely buy.
One of the main reasons to buy locally from a stamp shop is that they will remember you and possibly send some referrals. You may spend an extra dollar but it may pay off big.