Also, are you sure thats DivX and not Divx player? Divx was the old Pay-per-view format of DVD's that let you watch the Divx disc you bought for a set period of days, and if you wanted to watch after that, you would have to pay via a phone line. Divx was scrapped and discontinued, along with the discs and phone service.
I'm guessing its one of these, since RCA doesnt show that they have this product, and figured they would. Also I think the price is a little low for a stand alone DivX player.
More info
here.
Im betting that DivX players are rare and expensive, at least at this point in time. I wouldnt expect finding a good deal on ebay for a true DivX player.
Since DivX is a hack of Mpeg4 and MP3, you should probably also see Mpeg-4 support on any DVD player that supports DivX playback.
EDIT - BTW, just to clarify, I was refering to the original ebay posting.