Is Discount willing to refund your money, or are you stuck buying other tires from them. If you get your money back, spend some time in the Private Party Sale area for wheels and tires here:
http://www.e90post.com/forums/forumdisplay.php?f=111
You'll find both runflats and non runflats for sale, I'm sure there will be something for you that would get you through to the end of 2015. You most likely don't need an all season tire, so stay with the more readily available 3 season or summer tire category.
If you're stuck with Discount, then change categories to a max performance summer tire like the Continental extreme contact DW's or Bridgestone RE760 Sport.
If you sell your BMW privately, and don't have runflats, make sure to include a couple of these in the sale to lessen the fear of having a flat and no spare.
http://www.walmart.com/ip/Fix-A-Flat...r-Kit/21800629 If you trade in at the dealer, they may deduct money since the dealer will have to change out to runflats if they resell it.