After a bit of researching I decided ebay was my best option and I found the three cards I needed all from the same seller and at decent prices. They were all Buy-It-Now, so I made the purchases on a Saturday and just a couple days later, Monday, the cards arrived in my mailbox.
I found it interesting that the three cards that I needed were all horizontal cards. Other than that I couldn't find any other similarities or determine why they would have been missing.
I don't know if you can tell, but the stamp on the Willie Greene card is from the Devil Rays Inaugural set.
I contacted the seller and they apologized and sent me the correct card a few days later.