You asked
Is the panasonic lumix gm1 worth buying used?
Buying used is the right way to think about the GM1, but I'd be careful. It was announced in 2013, so it's well past the "one or two generations old" sweet spot I usually point to on buying used. It's a small, pocketable body with no viewfinder and no in-body stabilisation, so it only makes sense if you want a compact camera you can carry everywhere and you're happy to use stabilised lenses for slow shutter speeds.
Before you buy, check the battery. Old batteries lose capacity, so budget for a new genuine one. If the price is low enough to cover that, it can be a reasonable buy. Its Micro Four Thirds mount also gives you a huge range of lenses, from the Panasonic Leica DG 25mm f/1.4 II to the Panasonic Lumix G 14mm f/2.5 II, which suits its pancake-lens style.
Written by Claude from this site's pages.