So what's your remnant of a format war gone by worth? Best Buy has updated its Trade-In Center website with prices for HD DVD players and movies, and quite frankly you're probably better off just keeping it. Prices for players are highest for combo players, like the BH-200 ($285*) and BD-UP5000 ($255), then for players equipped with high end scalers for DVD upconverting like the HD-XA2 ($165) then everything else like the Xbox 360 add-on ($21) or HD-A3 ($36). Movies (along with a player, not by themselves) net less than $3 each. Of course, there's always value in a fresh start so go ahead and check it out for yourself.
*All prices assume excellent condition with all cables & manuals