I love the Nokians on my e46, they are unbelievably good. I agree they are pricey and hard to find, but if you're going to be keeping the x5 for a while probably worth the price for Boston winters. Did you check ebay for 8s? Might be able to onsey twosey a set from there if you have some patience.
On that note, if you still have your e70 set up and want to discuss selling them, PM me