What kind of outfit sells used telescopes anyway?

There are numerous sources for these gems. You could place them in many categories, but I like to put them into categories of shoppers:

"I gotta have one now."

Many retail telescope and camera shops selling new items, also sell used items. Links to some of these are included in the Members section under "retaillinks". There are also persons who specifically handle used equipment, and you will find some useful links to these in the Members section under "usedlinks".

"I want a deal, and I can wait for it."

A good place for this type of shopper is the "Classifieds" section of your local newspaper, particularly if you have one that is read by a large number of people. In many areas there are also specialty newspapers that are printed particularly for the sale of used items. These are sometimes organized according to subject, and telescopes can be found under subjects such as "Hobbies", "Sporting Goods", "Cameras", "Photographic Equipment", and "Miscellaneous". Yard sales can occasionally turn up outstanding finds as well.

Regional star parties and telescope making conventions can be a good source. Many of these have swap tables where there are great deals to be had on used telescopes, parts and accessories. Both Astronomy and Sky and Telescope magazines list the dates and locations of these events. Two of the largest conventions are Stellafane, held annually on Breezy Hill near Springfield Vermont, and the Riverside Telescope Makers conference, held in the San Bernardino mountains near Big Bear, California.

And don’t forget Pawn shops and similar consignment shops that may exist in your area.

"I know what I want, and I want to go find it."

Welcome to the internet. This is the leading source for used telescopes, and there is a nice set of links in the Members section under "netlinks". Is it safe to buy over the internet? Generally, yes, and most individuals are quite honest about the positive and negative aspects of what they are selling. However, never discount the possibility for "miscommunication." As with all transactions you have to apply good sense and keep in mind the Latin, "caveat emptor". So ask enough questions to be reasonably sure of what you are getting, check references, particularly at auction sites, and "let the buyer beware." You can make good use of the information in this site to identify the make and model of most telescopes, since the seller may not know. Also, ask to see an image of the item if possible, and at least ask the seller about its physical and optical condition. Then make your offer to buy accordingly.