You're right - I've also seen lots of last year's model for cheap. Buy 'em!
My guess is that they over-produced the skis. As a result, there's a glut on the market as the 05/06's are arriving. Bad for dealers, good for you.
I bought the 04/05 M:EX's, and wouldn't trade them for any other big mountain ski (except this year's version). In Tahoe last year, in 11 feet of heavy snow over 7 days in difficult conditions (fog and wind), the M:EX's motored through anything, and handled the hard stuff as well as the soft.
I'd buy exactly the same skis again. I just wish I'd gotten this deal.