Hi Akendrick57
to the Surface Engineering Forum.
I will repeat what Stephen said above. The new cost of say the basic wire or powder flame spray gun will roughly be around 3000 - 4000 GBP ($6000 - $8000), so that will be the ceiling on the value (unless its so old that it has collector value
).
It should also be pointed out that the cost of the gun is really only a relatively small amount when compared to the overall cost of setting up a thermal spray installation.
I would strongly recommend trying to get a copy of the gun/process manual and possibly handbook that would normally have been supplied with the equipment.