Personally, i've had good luck with the black-wrapped replacements branded "Cameron Sino". Upwards of around US$15 from Ali Express for most common batteries.
The Drive 50 uses the same battery as fitted to many Garmin devices, e.g. nuvi x0 series, nuvi 55/52, Drive 51, DriveSmart 5 from memory... and probably others. So you may even be able to source an original Garmin-branded replacement marketed for another device. Note that Garmin is a "fab-less manufacturer" (a contradiction in terms but meaning they don't actually make anything themselves) so everything is contracted out to be made to order, including their batteries. I've even fitted a Nokia phone battery to a nuvi 2xx by soldering the leads from the original failed battery to the phone battery which is the same size and specs.
Bookmarks