I found 1500 and 2000 grit at home depot. Surprising because the most I found there every other time I think was 600.
I really like the micro-mesh sand paper. But it's hella expensive. But even still it lasts a long time if you're gentle with it. The material backing helps to give a good rounded look on edges because it forms to your fingers..
Also tested a whole range of materials to put behind various sand papers. Cheap round sponges or the standard rectangular ones bent in half.. just an example. Helped me with the inner curves coupled with changing the direction of sanding..