These, with the lyre, are picking up slightly in pricing over the past couple of years. You used to be able to find them more often...but as time goes along...they are getting less and less AND the ones in good shape are getting harder to find. I predict they will keep going up in value over time.
I know I was looking for a lyre chair for over a year (that was in good shape and reasonable in pricing) and finally found ONE in Louisiana earlier this year. Too bad you don't have the chairs to go with it as well.
In my neck of the woods, $250 - $350 in good shape. In Florida, depending on the condition and where she is located, you may get this as well. However, if in a smaller town and in so-so shape...$100 - $200.