Hi Joanna,
I've bought and sold alot of stuff on eBay over the last few years, in fact, I will be putting the Ranger up there as soon as the new scope arrives. You can get fantastic deals on quality equipment (but there is alot of poor quality astronomy merchandise there as well).
It's very simple as long as you protect yourself by watching buyer and sellers ratings, the payment types they use & also keep up with the current scams.
As a rule I usually only purchase goods from individuals with a rating of 95% or more and a rating of 30 transactions or more. Plus if someone is buying from me I'd usually ask for Paypal if they have less than 10 transactions. Ratings can be spoofed but it is easy to spot by looking at the other party's transaction history, e.g. checking if all their previous auctions were for €1 items.
A word of warning though. If you are a beginning eBay user you will most likely get a much lower bid because many buyers will avoid individuals with low ratings (as Seanie mentioned). if you have a high rating the buyers will line up to bid.
e.g. I saw a Televue Renaissance 4 inch refractor on sale 2 weeks ago which went for slightly over €1000. The seller had a 0 or 1 rating. If he had a rating above, 30 say, it would probably have gone for twice that or more.
so if you have a low rating you would be best off getting someone else to sell it on your behalf or wait until the rating improves via more transactions.
oh, and for scopes you REALLY need to enforce that shipment will be trackable and insured to avoid damage, & to avoid someone saying they never received the item.
As to how long sales take, the standard auction times are 1 day, 3 day, 5 day and 7 day. I usually use the 5 or 7 days listings and payment is usually received on the final day.
Hope that helps some,
Trev
  