C.O.
If I change the price on an item I'm selling on ebay? It's usually to change to a Buy It Now price from auction.
It's possible the person did some research and found the item is more valuable than originally thought. Do an advanced search and find out if there are similar pieces being sold or that have sold (completed listings).
The seller will get dinged by ebay from having excessive shipping fees. You can call the seller on that.
I was actually surprised last month when I listed my boys old handheld game - a Pokemon Nintendo Gameboy sold in less than 5 minutes after listing it for $50 plus shipping. That was a first for me.
Why not send the seller a message and ask why the change? I would. Especially if it doesn't sell.
Hope that helps!!