Amazon is always my first port of call when looking for a particular book. Think of a title and someone is bound to have a copy for sale on Amazon.
Likewise when I want to reduce the size of my library, I generally aim to list on Amazon rather than eBay. There are several benefits a) it's a 'permanent' listing (doesn't need to be renewed every so often as on eBay), b) you can see what other vendors are offering their copies for and set your price accordingly. c) you get paid promptly, weekly.
My policy is if I can sell for at least a fiver plus postage then I'll list the book on Amazon. If I can't, it goes to Oxfam. Anything less than £5 and the net receipt of a few pence after postage, packing and Amazon's charges make it not worthwhile.
You will discover that many vendors on Amazon list titles for as little as one penny. They are only able to do this because of high volumes of sales plus getting the benefit of low postage charges resulting from contracts with Royal Mail or other carriers. (The Amazon postage allowance is £2.80; the minimum Royal Mail will charge me for a parcel up to 2kg is £2.90)
The three titles the OP mentioned are all available on Amazon
here and
here and
here
My personal opinion is that the Piercey book is probably worth listing, at a couple of pounds less than the cheapest currently available; the other two, probably not, unless they are in mint, as new condition.
(edit after reading H Harry's post) I don't think that people looking to buy an aviation book are necessarily 'collectors'. I buy lots of aviation books, read them and then move them on; I'm definitely not a collector. There are many similar 'out there' I suspect.