This tiny logger does a great job, especially when paired with the USB adapter for downloading the data.
Recently I purchased the Altus Metrum MicroPeak altimeters from Wildman rocketry. Ordering was fast and easy, my shipment arrived within 2 days. The MicroPeak is NAR Contest certified and small enough to fit inside an 18 mm air frame. After launch, a led displays peak altitude in flashes that you count. Simple instructions with a Lithium coin battery, a great value for a small primary or backup altimeter!