Cheapest it's been to my knowledge..
Simple Value Cordless Screwdriver 3.6V £2.99 Was £6.99 Argos (Free C&C)
Screw in. Screw out. Done. Affordable and efficient, this Simple Value screwdriver is easy to use and has an ergonomic handle for comfortable and easy holding. Helping make those everyday jobs around the home a lot easier, this powerful 3.6V screwdriver, also features a 50mm screwdriver bit and 1 torque setting. 3.6V battery power. 1 speed setting. 1 torque setting. Max torque 2Nm. Accessories included: 50mm screwdriver bit. Size H5, W12, D18cm. Weight 0.28kg. Batteries required: NiCd x . 3 to 5 hours charging time. Charger included.