Here's the latest edition to my map collection. This one is a first edition (1915) sheet 57D which covers the Somme battlefields at a scale of 1:40,000. Although not a trench-map (they are at a scale of 1:20,000 or less), it is still a valuable tool when researching specific events, and it has come in particularly handy while I have been working on my new book about Pte Smallshaw of the Accrington Pals and events which took place in squares 23, 29, 30, 35 and 36. This map is about as close to 'mint' condition as you are likely to get. It fits in well with my collection of other map-reading material from the Great War too!
I was astonished to see on eBay the other day - a trench map (sheet 28 NW) of the Ypres area fetch £260. I have that one in all different available scales of 1:100,000, 1:40,000 and the copy with all trenches marked at 1:20,000.