There are several microscopes on Amazon for under $100 that would suit young students - Amscope and Swift each offer several that might work for you. For example, (not a recommendation) - https://www.amazon.com/SWIFT-Microscope-40X-1000X-Magnification-Capability/dp/B07NBTKS1K/ref=sr_1_31?dchild=1&qid=1601831768&s=electronics&sr=1-31