I posted an explanation of Amazon's deal elsewhere: I pre-ordered BBM for $16.98 and got free shipping with 2nd-day air by signing up for a 3-month trial of "Amazon Prime."
Actually, I started my free trial over a month ago, but even without it Amazon gives free shipping on any order over $25, so if you need or want something else, you can get free shipping that way. However, that's with UPS ground, 3-5 business days.
If you sign up for the free trial today, wait until tomorrow for your Prime membership to work its way throught the system, then order BBM. You'll get it on April 6.
Unlike free trials at other companies, Amazon Prime allows you to "pre-cancel" your free trial. Once your trial is active, click on "Your Account" then go to "manage your Prime membership." There you can set your trial to expire... I think it's something like "Do NOT upgrade to Prime when my free trial expires." This way, you don't even have to remember to cancel, and you'll still get 3-months' worth of free 2nd-day air. Sweet!