I keep a record of what decks go for on ebay UK.
Not all, just the ones that interest me, that I might want to get someday.
So I know what would be a fair price to pay, or to expect to pay.
Money is tight. I want to buy decks, but I can only justify buying them if I can tell myself I am getting a good deal!
So, all this is just so I can convine myself it's OK to buy more decks!
I only have one record of a Ukioye. It went for about £12.50.
I have three for the fantasy showcase.
£25.00, £21.00, £13.00
None of these are what I would call very much.
They might sound like a lot when converted to dollars, but that is an effect of the exchange rate, and (I believe) gives a false impression of British prices.
But neither are they dirt cheap.
I very rarley keep notes on American prices.
Perhaps someone else does.
Like other people have said. It's worth what people want to pay.
So, all this only means that I have a record of what one person thought the deck was worth to them.
But I hope it helps you a little bit in what you are trying to find out.