I've read various accounts of fellow bloggers' experiences with Checkoutmycards.com, all of which have been extremely positive. Over the Christmas break, I took the plunge and decided to finally check out the Checkout process.
In a nutshell - I'm impressed. The inventory is expansive, the web-based storefront is easy to navigate and fairly intuitive and the prices are very reasonable. You can view high resolution front and back images of all cards, and point and click your purchases into a shopping cart. There's an asking price for the cards, and a feature that allows you to submit a counteroffer if you deem the asking price to be too high. I used this "make an offer" feature a few times, and had all my offers accepted.
I ordered cards from about a dozen different "dealers" and everything came from Checkoutmycards in the same box. The shipping charges seemed a little high for my liking, but that would be my only minor complaint. I was able to find several cards which had been on my wantlists for at least 10 years, including these two 3D beauties.
This is the closest you're going to come to a virtual baseball card show. The real thing is still more fun, but as it gets tougher and tougher for me to make the various shows in my area, I'd gladly spend some more time (and money) shopping here.