The first step is to get your horns. I was able to locate a set at an antique store. You don't want a set that has been dry rotted in the sun. This is why mounts that have been kept inside are good candidates. Now keep in mind all this is/was all new to me, and i'm no sheep expert, so ill go through some of the concerns i faced when finding a set. First off think of the horns cross section as a triangle. What we care about is the side that faces up at the base and continues on back down the horn. In other words, if you were to put your finger right in between the horns in the middle of the sheep's forehead, the surface closest to your fingers that runs up and back over the head is the surface that provides the bow limb. The other 2 sides don't matter, you can salvage them for tip overlays or other projects, but if there are cracks and damage in them it is of no consequence to the bow.
Lets talk wild vs domestic. Your wild sheep candidates (to my best knowledge) include Bighorn, Desert, Dall and Stone. I have read that the Dall are thinner and have less material to work with. I was told that the domestic breeds are even thinner and have more curls, therefore you fight the issue of your limbs wanting to twist back into their original shape. This is an issue with any sheep horn but apparently more so with domestic sheep horns. The consensus was domestic might work, but expect a lighter draw weight bow(even having said this i have located a domestic set of horns i might end up trying just for fun). A good set of wild sheep horns will run $300-$600. You want to look for cracks that may indicate someone using a hammer to remove the horn, or cracks from where they have been fighting. Now, the first thing i noticed is that all these horns have surface cracks, and some imperfections from fighting or just how the horn grew. What were concerned with is true cracks running into the core of the horn. I used an LED flashlight to carefully inspect down into the cracks to see how deep they went, some were almost 1/4" deep but angled in a manner so as not to go straight down into good horn. This is the first place where having some prior bowyer knowledge helps, being able to identify what will "rasp out" and what might be a deal killer. I was told by other sources its always a bit of a gamble and you never "really" know what you'll find inside. Keeping this in mind, I spent the better part of 30 min analyzing the set, sweating bullets, and then eventually pulling the trigger and deciding to give them a shot.
The pics are a bighorn sheep(darker horn first pic) vs a domestic sheep(lighter color second pic). I was actually told the lighter set was Desert sheep by the seller but Tom didnt think it so and i passed on them(im open for any opinions on this set from any sheep experts here). As i understand it the color is not necessarily indicative of one being wild vs domestic it just happens to be the case on these pics. I actually found another set of Bighorn or Desert sheep(not sure which) that is more of a light brown tan color, not the dark grey color. I might actually pick that set up too for another bow.