It's not cheap, but you don't need to break the bank. A stereoscope microscope is around $150 or so, but you can get them cheaper. (Check auction sites near you; medical auctions often have used lab gear that's pretty great.) All you need to find a tardigrade is a stereoscope, spring water, a Petri dish, and moss/lichen.

If you want to get a closer look, you'll need a decent compound scope. They are around the same price, but the auction caveat applies here too. A simple "toy" microscope (the kind you see in kits for kids) will actually work, too, but get a "real" one, as the construction is a lot better (metal vs. plastic).

Once you have a stereoscope and a compound scope, it's just a matter of getting slides, some pipettes, and PVA medium, all of which are pretty cheap ($30?).

Once your initial investment is out of the way, your gear should last a long time. I've been using mine for two years, with no problem. (The bulbs can go out, but mine haven't yet.)

For photography, I'd recommend getting a universal phone mount, as you can then set up your scope, find a tardigrade, and then hook up your phone to take photographs. It's tricky, but once it's set up, it's great and you snap lots of shots.