I'm considering selling my copy of TSR's Boot Hill 3rd edition core book. I bought it a little over a year ago when said book was going for a hefty price on eBay and am unsure what it is worth now. It has a small amount of wear on the front, bottom, right-hand corner but is completely intact (the map is still folded and attached inside the back cover of the book). If I were to start an auction listing today, what would a reasonable opening bid and buy out price be?

[Edit: I should note that, other than the aforementioned shelf wear, the book is in excellent condition.]