I still don't get what's wrong to ask the price.
Fair enough. Here's why.
Most farriers get that first call via voice message as they are usually under a horse or otherwise busy when the call comes in.
When they listen to the message it all too often sounds like this:
"Hi! I'm calling to see how much you would charge to come out and trim my horse? You can reach me at 555-PasturePuke".
The average farrier will "read" a lot into this call.
I don't know how many horses you have. I have no idea how far away you are so no idea what it will cost me to travel to your location.
I have no idea how long it has been since your horse was last trimmed/shod so don't know if we're talking about a 30 minute maintenance trim or 2 hours worth of corrective work. I also don't know if we're talking about a well trained show horse that stands like a dream or some ill-broke pasture puke that you just got from the local EPM rescue. I don't know what the intended use of this horse is. Is it a light horse? A draft? A mule? I have no medical history or current status of the animal. I don't know if you have a barn with power/water/light or if I have to stand in 6 inches of paddock muck while trying to get a therapeutic package on a lame horse in an ice storm.
Moreover, you just told me what your horse needs. I can't tell you how many times I've shown up to a new client who requested a trim and see a horse that is desperately in need of shoes. I also see a lot of horses that would do just fine with nothing but a trim but the owner insists on shoeing the animal. There's a professional standing right in front of them that does this every day for a living and is probably highly qualified to suggest what will best meet the needs of their horse, but... people don't ask.
Most important, that voice mail message suggests to me that your first priority is cost and you're probably looking for the cheapest guy in town. I understand but to be honest, I don't want to be that guy. I know how that guy runs his business; I know how little training he has and I know what his priorities and work ethic are.
No, I'm not that guy and don't want to be. In the longer term, you'll be glad I'm not him. So will your horse.