Hi banditele,
First let me say that I've never purchased off of ebay as of yet. Now that's not to say that I won't in the future, if I find a knife that I'm interested in, I just haven't yet.
But I have purchased used knives online. Yes, I haven't been able to actually handle these knives but I have
seen pictures of them. If the description and pictures supplied don't give you a warm and fuzzy feeling simply email the seller for further required information and/or pictures. Most sellers are usually more than willing to provide this information upon request.
There are some great deals out there on used knives listed on the internet for the collector to find and take advantage of. I love to find them. It can be as much fun as going to a flea market and coming across a great deal. Actually, it can be even better because while your surfing for deals on the net you're usually in your home and can use your books (and yes the internet too) as references to ensure/confirm that you are getting what you actually think your getting and for a fair price as well.
For example, I recently purchased an "Excellant/Near Mint" Kinfolks Knife & Axe set made between 1925 - 1948 for $75.00 from an online antique dealer. That very same week a very similar set in similar condition sold on ebay for $282.00. The next week a matching axe (only - without the knife) in "good to poor" condition sold for $78.00.
Now did I get a good deal?
Am I happy with this particular online "never handled the knife" purchase?
You bet I am!!

Not just for the obvious but because I bought something that I was familiar with, something that I liked, and for a price that I felt was fair for the condition that the dealer was reporting it to be in.
This all added up to a great purchase for me.
Now I'm sure that there are a lot of no good a-holes out there who would lie about what they're selling trying to cheat us but I will not spend more than I'm willing to loose. If I tell myself this before I make this type of purchase than I usually find I'm more than happy with the results.
Also, I mentioned that I do this for
used knives but I should clarify this a little more. I will
only do this for used knives that are not being produced anymore. If a knife is still in production, or if it is so
new that it is readily available, it's not something worth taking chances on in an "unhandled" internet purchase. I figure why bother to risk any investment in a used/new knife that I can, in most cases, find
new/un-used for usually not much more. I say not much more but it actually may be a considerable amount more but that can also be the price for piece of mind.
*Note - The exception to this, as VampyreWolf has already pointed out, would be buying here at BFC from a fellow forumite that has favorable feedback.
Hope some of this is what you were looking for.
Happy knife-hunting.....
--The Raptor--