If you don't approach it as a money-making operation, you will certainly lose money, even if your motivations are pure of heart and you think you're just finding new homes for orphans.
I've got a 4-digit, 100% eBay feedback rating, split about 50/50 between buying and selling (not just astro stuff, but a diverse assortment) over nearly 15 years. Not a business but strictly oriented toward my hobbies and those of my late mother. Packaging & shipping takes a LOT of time as well as money for materials. Even putting together a decent on-line listing takes time. Buyers rarely appreciate a careful packaging job, from my experience, and don't understand that even if you pack something in plate steel, the carrier can find a way to damage it and the contents. Few want to spring for insurance, and even complain about shipping costs- blaming the seller- even when less than what it actually cost to ship. Some people can't be satisfied unless an item is absolutely free and they get it immediately. And even then they'd find something to complain about.
There are great, understanding buyers out there to be sure, but they are the minority.
Good luck Joe, I hope you can make it work!
Thanks, Chuck; that's good advice. Again, I never thought this would create a food-on-the-table income; I only hoped I might cover at least most of my costs. I would hope that nastiness of customers would be mostly alleviated by selling on Cloudy Nights Classifieds, in the hope of finding buyers who understand the wares, but the cost and hassle of shipping would surely remain a problem.
The more I read everyone's thoughts, the less I think the project would work, except perhaps in some cases where I happened to buy a more valuable scope for little money. Trouble is, if the scope were that good, I'd want to keep it! Reversing this, I've seen some scopes advertised that would have interested me, except that the seller said, "Must pick up; I can't ship."
I'll not consider this idea dead-in-the-water. I'll see what scopes appear for sale, and consider what I can do with them. I like the idea of having classic scopes pass through my life and on to other astronomers, rather than into dumpsters.