I am not sure if you have thought of this before, but I sprayed a couple of knives for some men who worked for me, with polyurea. That is the stuff they use for bed liners in dump trucks and pick ups. The cost to do a knife handle is pennies at the most.
To give you an idea of what the real cost as far as materials are to do a bed liner for a pick up truck, you are looking at about $45. Now I have not sprayed polyurea in a couple years as we just spray foam now, but still, the cost to do a knife is small. I am not sure what the costs are now though.
If you ask around and find someone who sprays that stuff, you will have the best handle material you can get as far as any type of dip or spray on. Maybe go into a shop and show them what you want done and while they are spraying a bed liner, they could take an extra 10 seconds and do your knife handle. I mean it is that fast and the stuff sets up in seconds as well.
All they would do it hold the blade in a clamp over the bed of the truck and give it a VERY VERY quick hit with the gun and you are done. Take in a dozen knives and a twelve pack and I bet you would work something out.
Ask them how they want the knife set up when you go in. You can not just tape off the part you don't want sprayed as that won't work. What we did was take a couple of pieces of wood and put the blade in-between them and then sprayed the handle. The over spray was then cut with a razor and buffed smooth. The wood gives you something to hold on to while spraying as that stuff comes out at about 120 degrees.