dbocca,
Welcome to the forum. Sorry that you have been taken, it sucks not only for you but also for our hobby. Sadly he is not the only seller who is taking advantage of others and as your post states; education is key. Education not only with the material but also becoming well versed in
ebay's 'loop holes' and how unethical sellers use them to their advantage. As you have found out, this can range from simply trolling for suckers all the way to outright fraud.
When we hear or read about some fantastic deal that someone got online it can feed our courage for taking buying risks. But we should never underestimate the extent that some sellers will go to exploit our risk taking and system short-comings.
ebay's rating system is a good example. While some sellers try hard to use it correctly, buyers need to look beyond the surface. For example, every buyer should look closely at the sellers name ID history before making any purchase on
ebay. If you see something like this...be wary.

Ask yourself, why would a seller want to go through so many name changes? Sure, a seller might want to change his name once or twice over the years, but why build a good reputation and then potentially lose the good will and your customer base by frequently changing names?
Unfortunately trying to use a sellers 'Top Rating' score or number of feedbacks is also full of pitfalls. It is far too easy to simply to use
ebay's system, policies, and procedures to rip-off buyers. Any thief or crook can buy an existing Top Rated account in minutes online. This gives them apparent instant 'creditability' if a person does not look at these issues critically.
There are some great sellers online, the trick is to find them but don't expect that they will be letting good material slip through their fingers. Quality sellers know what they have, what it is worth, and in the vast amount of times will identify it correctly. And they certainly won't be using 40—50 accounts to move material between them until they can land an unknowing buyer.
The importance of your post cannot be understated, becoming a well informed buyer exceeds beyond simply knowing the material. Just as we have to research the material we have to research who we are dealing with; look for warning signs. Those sellers who bristle at buyers who ask questions (or even refuse to reply), sellers who list high dollar material but don't bother to offer high quality images (including backs of stamps), sellers who have multiple name changes, sellers who say in their listings 'some material may be expertly repaired' are all potentially danger signs. Don't just look at a Top Rating or the number of feedbacks as sign of confidence, don't count of being able to successfully return item as a fallback position.
Start slow with a new seller, don't drop big money with a seller until you are satisfied with previous buys. Dip and closely inspect everything bought and send items out for expertzation. Use sites like this forum and Stamp Smarter to arm yourself with knowledge; knowledge is the only ammunition in the war against bad sellers.
Don