Oops, Sorry, I thought you have two publications. The Bentley and an Orig Drivers Handbook. You only have the Bentleys I believe. My opinion on value for the what appears to be a well used Bentleys is-Not Much. Mine is on my shelf in the shop and sees regular use.
I see lots of both on the US Ebay in variious permutations of revision and editions.
Just go to Ebay. Look at the for sale listings and then go to the Advanced Filter and look at Sold Items. You will find both.
For Sale tells you "pie in the sky" price, Sold listings brings you back down to earth.
The Bentley manual is commonly available as a new publication and used. Very useful book.
Used they have sold on Ebay from between $9.99 and $89.98 US. I saw a number sales on the US ebay.
The drivers handbook are also numerous and sell between $25 to $102 for what appear to be different editions than your's. With a quick check I did not see yours. For sale prices run up into the $400s and here's an early 3.8 Non-Issured book that sold for $375. Someone HAD to have it!
https://www.ebay.com/itm/355611460407?_ ... R5LDq5O8ZA
I would say the earlier the better as far as value goes and I can't tell what model your's is for.
CONDITION is everything in this sort of thing.
Try your search again and you should find better guidance.
I have the Bentley in what looks to be about that shape and also an 3.8 manual myself.
Use these searches on EbayUK. Lots of listings show up. Sold listings is your price guideline
jaguar bentley workshop manual
jaguar etype drivers handbook
Appear they are cheaper in UK than in US