Queen Elizabeth II -- Royal Panties For Sale ... on eBay

You really can find anything on eBay ... even Queen Elizabeth​'s underwear , which can now be yours ... if you have a few thousand bucks to blow.

As TMZ previously reported ... the royal panties come from the estate of the late "Baron" Joseph de Bicske Dobronyi ... who wanted to auction them off after he died with the help of a British auction house, Hansons Auctioneers. But it didn't go as planned ...

A rep for the late Baron's estate tells TMZ ... the auction house was difficult to work with. He claims the auction house never gave the item enough publicity and were more concerned with the approval of the royal family than selling the goods.

We're told the estate was tired of waiting around for Hansons to find them a worthy bid ... so they demanded the underwear back and put them up for sale on eBay for a limited 10-day auction instead.

Now you can have a piece of the royal family for the low, low starting price of ... $3,999.