Keep a single barrel shotgun in the truck, they make good squealing horns. It hard to find a good cow horn for under a couple 100$ actuall the best thing to do is train your dogs to come to truck horn. It pretty easy.
Size just depends on the size the horn is when I start. They are getting harder to find all the time. I have made them that wind up 14-16 inches long and have made them that are as small around 8" long. The small ones are really hard to blow. I used to be able to blow them but I guess age has caught up with me. I live near Harrison, Arkansas... It is about 45 minutes south of Branson, Missouri..
I understand. What I have done some in the past is take several pictures and send and record the sound of the horn and send it as well. I realize that is not like being able to test drive it. I enjoy making them when I have time and can find good horns to work with. Mr Pulpwood. Where do you live? The ones I have sold in the past have just been shipped via US mail. Not very expensive.