FamilyTreeDNA sent out an email to person's who have tested with them that has sale prices for upgrades. I hope that the surname groups are taking advantage of this and upgrading the 12 and 25 marker kits to 37 markers. I'm not sure how long this is running though I would imagine it will end when the holiday sale ends.
You may also be able to find coupon codes which would save even more money on the purchase. Check your FTDNA account(s) for further info. Logging on the account you want to upgrade and then clicking on upgrade or CART(upper right corner of the page) will show you what is available for that kit.