I think in general, used car inventory is on the low side and doesn't seem to be rebounding. One thing I heard from a few dealers that is driving this is there is a lot fewer 2-4 year old off lease cars right now because back then new car sales including leases were way down. All that tends to drive up prices for used cars - purely supply and demand. And sure - seasonally sports car prices go down over the winter and rise in the spring and into the summer, and opposite of that for SUV's / AWD cars. I would think the market for your wagon wouldn't be so affected by the seasons since it is just a normal car not a sports car or SUV. That said, it is generally harder to sell a car going into the holidays and always easier in the spring.

Good luck with whatever you decide.

BTW - my X5 replaced a Audi S4 Avant and I am very happy with the added space in the X5 which fits our families needs better. I went to a sports car DD which is something we can get away with more here in CA. But the X5 is still driven daily during the week by my wife. I get it when I need to haul stuff or go skiing.

__________________
2003 4.6is - SOLD
2003 M5 Imola
2008 Mini Cooper S
2011 Mazda CX9