Does it come with the original box? The EB ones usually are in the EB cardboard plain box w/ DC on it, so it might be worth the premium if you get the original box & docs with the system.
If you don't have any games at all, you may want to seek an auction with several games you wanted to get included. If anything, you'll get things bundled together and won't have to pay 3$ for a game and 5$ for shipping per game. I still play my DC, so it's worth checking out just for some of the original Sega titles.