I'm a fan of LDCs on cello. YMMV. I also found the AT2020 to be nice on cello; it's sort of a MDC, I'd say, being in that range between half an inch and an inch.
On grand piano, I use
a Shure VP88, but obviously that's not in the $300 range. I've used a pair of MSH-1 mics, and that sounds reasonable. On upright, I like a pair of MSH-4 mics. They take the edge off a little.
For djembe... it would depend on the size, IMHO.
For a larger drum, probably a large diaphragm dynamic like a kick mic.
For a medium size... well, my best conga sounds came from an old Shure Unisphere III, so for something more on that scale, that's an option. (The Unisphere III is pretty similar to an SM58, but a bit less tubby, IMHO.) There's not much high frequencies in that, so everything the Shure dynamics roll off tends to pretty much be noise anyway. I'd imagine that would do well for a similarly-sized djembe, too.
For smaller hand drums closer to the size of bongos, I've been happy with an AT2020.