Celestron C90 'Maksutov Cassegrain' telescope and tripod, $25.

A familiar tried and true formula - an expensive item that is geared toward a hobby that many people are interested in, selling for a fraction of what it would costs to buy new. I could bore you with the fact that Celestron telescopes have been around for a long time and are very well made units used by many amateur as well as professional astronomers, but it's not necessary to go there in this case. All you have to do here is, in your head, compare the price I can buy this telescope for, with the lowest price that one of these machines could possibly sell for new.

This telescope is mounted on a tripod that, as the pics should show, obviously cost plenty. And it even came with a box of extra stuff that allows the telescope to track along and keep whatever it is that you're looking at in view as the Earth rotates. Now, do I really have to know just what this setup is worth before I make the purchase? Not really, all I have to know is that at $25 there's a good deal of profit built into the deal. Remember that in this business, you don't have to know the specifics about everything, you just have to make sure of the spread. So, all I have to do is ensure that there's always a spread between what I can buy for and what I can sell for, and I'm safe. In this case, I could throw away the tripod, electronics and everything else, and sell just the telescope for over $150.

When the seller saw me looking at this telescope, he ran over and immediately confessed that the lower tripod bracket was broken, which is visible in the pics here. If he had told me that something insude the telescope was broken, I'd have been concerned. But I can fix a little plastic piece for a few dollars, or even let the buyer do it. What's good here is that the seller felt compelled to disclose this very minor problem to me right up front. I like that.

There's an interesting aside here that's not really too important, but I should mention it. Notice the short, fat shape of this telescope, which looks nothing like the long, thin telescopes we're all used to seeing. There are two basic types of telescopes out there that you're likely to run across - the refractor and the reflector. In a refractor telescope, the light takes a straight shot, entering one end and getting refracted, or bent, by the lenses as it passes through the telescope on its way toward the eyepiece.

A reflector telescope, on the other hand, uses mirrors instead of lenses, and actually folds the light over several times inside the telescope, reflecting it back and forth inside the telescope before finally presenting it to the eyepiece. This reflector setup allows for high magnification in a shorter package, and if you'd like to know more about how these things work, a quick internet search will turn up dozens of sites. The point I want to make here is that its possible that people may not have associated this squat little thing with a high-powered telescope when they saw it.