My personal experience has been very good and have found some of my most collectible, favorite dulcimers on E Bay, Bill Davis, Bob Mize, John Stockard, Warren May, and most recently a Homer Ledford in fantastic condition.
My biggest disappointments have been on the selling end, and with the USPS that completely destroyed 2 that I had sold and packed in my usual type A method.
I am fortunate enough to have not been let down by any I have purchased sight unseen and sound unheard.
My only surprises were my first accidental discovery of Just Intonation with an on line purchase, took me awhile to figure out that it wasn't a defect, it was built that way, and my first "floating bridge". I had always had fixed bridges, so when I went to restring it the bridge fell off and I was horrified thinking I had broken it.
updated by @george-desjardins: 08/07/16 07:12:55PM