Hi Colin KC
I was at Beaulieu boat jumble earlier this year and for the first time there was a second hand tool stall there.... It was a very good stall too. I bought a hand slasher and paid £15. Bill hooks were priced around the £10---£15 mark depending on size make and condition. Thay all had good handles and were sharpish.
I have several styles of billhook dependant on the job to be done and species being cut. I even have a billless hook(I cut it off!) this is my primary bushcraft tool as opposed to the GB axe. It lives in a wooden sheath made from Yew front and Larch back hollowed out and held together with copper rivets (I have only just started to learn about leather sheath making)
I hope this is of help.
Swyn.