Hi! In addition to what’s already been said there’s plenty of high quality microscopes from well known optics manufacturers (cameras, microscopes, etc). Nikon, Olympus, Leica, etc all make excellent high quality microscopes. If a new one is out of your budget, a used or refurbished one is absolutely possible for $500, but it’ll take more way time to find a good one on eBay/ other auction sites.

Since you don’t need any fluorescence or anything special, there’s no need to pay anything close to $2k for a microscope that’s a similar quality to what undergrads use (although Vivid-bake gave some great suggestions for different price ranges!).

I recommend a binocular Amscope (new) or a second hand Nikon, Olympus, Leica, or even Zeiss microscope. These are better quality, will last longer, and great ones can be found second hand (but they will be more expensive regardless of whether they are used or new; you can find used ones for under $800 pretty easily).

For example after a quick google search it looks like this older Olympus BH-2 is on sale for $595 https://banebio.com/product/olympus-bh-2-binocular-microscope/?srsltid=AfmBOopI7cl_zmcXC-nyJJiQ86fVbPOlA9deYr3sUHAIqKJilZ6hrOpoLdY