It would be great if you could post pictures, it would help in grading. A Dark Tower: I The Gunslinger in Near Fine or Fine condition can bring big bucks.
If you put it up on ebay take the maximum (12) amount of pictures, with the dust jacket on and off. copyright page is a plus to with publishing info to help identification.
DT: I 1st edition is a very collectible book, 10,000 print run in 1982, by a small independent publisher Donald M. Grant. does the front inside dust jacket have two prices? one for 60.00 and the other for 20.00? If both are there take a picture of that also it helps to prove its a 1st edition dust jacket the 2nd edition only had the 20.00 price.