There are LOTS of wireless base stations on the market that will work with AirPort. Shop around and find the best buy. Anything that supports "802.11b" or "WiFi" works with AirPort, so that end isn't a challenge. The problem for the shopper is finding boxes that allow you to configure them while using a Mac OS. The better ones use an internal web page, so they're independent of what kind of computer you have.
I don't have any experience with the D-Link base stations, but my Linksys WAP11 has been cooking along just fine for over a year without any problem. The only problem you would have with this item is that it needs a PC to configure it. On the other hand, Linksys makes a 4-port router with a built in wireless base station, and it's configured through an internal web page. They are found for $150 or less, and they tend to have much better range than the AirPort Base Station.