I just ordered the Movie Advanced (it's fairly cheap, and should be easy enough to resell should I not like it).
I will point out that a DS version is suposed to be in development, and from what i read at Engadget we might have a North American Play-yan the same time we get the GB Micro.
http://www.engadget.com/entry/1234000643044876/
So my sugestion would be to pick up a movie player advanced (and sell it in the fall) or just go with out a movie player for the summer, because Movie advanced DS, and NA Play-yan will linkly be better choices then the JPN play-yan.