Amazon has the Irwin 6-1/2" Standard Drywall Jab Saw (https://www.amazon.com/dp/B000B3EGN8?tag=quackdeals-20) for just $3.60 (originally $6.89). Free shipping with Prime or on $35+ orders. Clip the coupon on the product page for an extra 10% off. This handy saw is perfect for drywall cutting and other home improvement tasks, and it's currently at a steal price (48% off!).
(https://m.media-amazon.com/images/I/51FCvpUtdZL._AC_SL1500_.jpg)