When it comes to old bows, they are worth whatever someone is willing to pay. No more, no less. If you put it on ****, the bidders determine the value.
There is more interest in hunting weight bows rather that target weight bows. However, if two or more Groves collectors get into the bidding, the price will go up. Other than that you will have bidders just trying to pick up a nice bow cheap.
That is the best answer I can give you.
A hardcore Groves collector may be able to give you a more accurate answer.
I have over 80 bows hanging on the wall. Three are Groves bows. I will not know their value until I try to sell them, regardless of what I paid for them. They were worth what I paid for them at the time as other bidders set the price. If I ever put them up, I may or may not get my money back. Off hand,I don't remember what I paid for them.