I can only add one thing to what the others have said and I think it is often overlooked by us collectors in the quest to add to our "investments"
What was a "rare" find in the antique shops of ten years ago, is no longer so. Unless the item was handmade and the person susequently died, most goods from the Victorian era onwards were made in hundreds, if not thousands.
Ebay is a worldwide (thats the important point)marketplace of 19 million items each day. What you want will turn up sooner or later, but it is a random thing - you may have to wait a year and then three appear!
This has happened to me, a very rare camera made in penny numbers, because the manufacture of it broke the firm, had only appeared twice in three years (Both times $200+). I thought this was excessive, so when one appeared last year, I was well pleased to win it for $80 (AS again!).
This year another came up for sale and I was practically the sole bidder at $35 (wrong description again!) Last month another came up and it didn't reach its reserve and after some correspondence I paid $90.
So I now own three (OK, OK, thats the question my wife asks!) Hopefully they are an investment - come off it now, what else can be fetch twice its value instantly? NO, thats not a`silly argument - misdescription and poor description are the reasons many goods don't reach their proper value.
Good hunting - be patient - never ever be influenced by other bidders to join a bidding war, walk away if you have to!
As a simple test of the veracity of this statement. Choose any scarce object you know about - look at the bidding patterns. It is only those with low feedback that pay excessive prices (as a general rule, I might add!)