The ICOM ID-51A is a great choice for a beginner handheld radio, as long as you are close enough to a local repeater or plan on using a DVAP or D-Star Hotspot... With that said, one of the cheapest radios to get started with is the ICOM ID-880H, which is an excellent dual band (one band at a time) D-Star mobile; however, programming is slightly trickier, but not all that bad to be quite honest if you read the manual.
Another option is the Internet Labs DV Dongle; this is a device that connects to your computer (Windows, Mac, or Linux) and allows you to utilize your computer as the interface into the D-Star gateways. While not "real radio" as some would describe it as, it still allows you to interact and check out what D-Star has to offer. A word of caution though; DO NOT use the internal microphone array on a laptop, the audio generally sound terrible, it picks up all the room acoustics, etc. If you decide to go this route, purchase a good quality headset for the computer you are using and make sure the headset (if it's USB) is on a separate bus from the DV Dongle; there have been issues with garbled audio when two USB devices compete for each other on the same USB bus channel.
If you are thinking in terms of more longterm involvement with D-Star, might I suggest ICOM's newest mobile, the ICOM ID-5100A; that's is the cat's meow of dual band mobile radio to-date!
Good luck and welcome to D-Star!
Jerry, W2GLD