I love microscopes. Always have. I still get a kick every time I look for crystals in joint fluid. As a kid I had a really cheap thing but despite the horrible resolution I spent hours making slides of all sorts, mostly bug wings if my memory is good. When I had kids I could hardly wait to get a microscope to show them the wonders of the micro world. I knew as well that when the time was right I wasn't going to get one of those cheap toy store models. I've seen many of those come and go, mostly go. At 1000X, the fuzzy resolution and shake of the light plastic bases are more likely to instill nausea than awe. I think that those microscopes may well be the principle cause of kids dropping science. "Dad, I'm going into commerce because when I was five you showed me something sciency and it made me throw up". Not my kids. What I got was a 20X-40X dissecting microscope. It did cost about $250 but it has been worth every penny. No set-up necessary, just gather up the bugs, dirt, and household objects and turn on the light. That's it. The kids can easily do it all themselves by the time they're four. An all-time favourite subject of mine is mosquito larvae and pupae. At 40X the pupae look like creatures from the movie Alien. Spider eyes are sure to impress as well. Fact is, I'm still looking long after the kids have faded.
On a final note, one of the very few financial benefits of being a rheumatologist is that you can deduct a dissecting microscope as a professional medical instrument and you might even use it for its intended purpose in capillary microscopy.
On a really final note, this topic arose from a post by PZ Myers at Pharyngula.