IRWIN Tools Standard Drywall/Jab Saw (2014102) for $3.11 at Amazon and one day free shipping with Prime

Features:
Rigid blade delivers solid cut control.
Bi-Ground teeth delivers fast, smooth cuts.
Hardwood handle is comfortable and balanced.
For roughing in drywall, cutting out HVAC, plumbing, and electrical openings or cutting ceiling tile openings.
https://www.amazon.com/gp/product/B000B3EGN8