If you're looking for a new smartphone, this is apparently the weekend to go shopping. Following Radio Shack's promise to chip in a $100 Google Play credit with purchase an HTC One and Walmart's deep iPhone discounts, AT&T has quietly tacked on a 50% discount to all smartphone purchases under $199. This puts devices like the HTC One, Samsung's Galaxy S4 (and the S4 Active), the Note II, both of BlackBerry's latest handsets and iPhone 5 at an enticing $100. Naturally, Ma Bell has attached the usual hooks: the deal necessitates a new 2-year agreement or contract renewal, and in-store purchases require a trade-in device to activate the discount. Not a bad deal if you're hankering for new hardware -- just make sure you don't walk away with buyer's remorse.