test drove the Countryman and X3 today. Me and the wife are also looking to replace our X5.
I see two issues...
first has already been mentioned... under 25K won't get you very much in the Countryman. Basically a base model 2 wheel drive plus all the taxes and charges will cost about 25k.
the second issue is the amount of car seats you want. Even with a rear bench (i'm not even sure they have that option yet) There is no way to put three seats in the back.

I was impressed with the countryman, mind you I drove a turbocharged all4 version. I was expecting the car to be sluggish and the ride to feel "loose" or floaty. To my surprise the car felt just like my ClubmanS or CooperS, except the seat is much higher, like a captain's seat. The back seats can be pushed back and forth a few inches which is great for when you want to chose between cargo space or rear leg room.
I was impressed at how roomy it is in there.

Problem was that the new X3 was very, very good and is pretty much the size of our E53 X5. With all the bells and whistles the CountrymanS all4 was the price of a spartan X3. X3 is my choice.

But OP, if this is only for a couple of years then take the advice of E61Silver...
buy a used honda minivan, with the few thousand that you save you will have enough gasoline money for the next two years (milage may vary!). And then when it's time to buy your X5, finding a buyer for the Honda won't be an issue.

I'm on the same boat... I know that a minivan is the reasonable way to go, but I just can't stand the idea of owning and driving a Minivan

Goodluck

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