Ratchet wheels aren't hard to make. Unlike gears you don't need a special cutter as the profile is just a 90-degree triangle.
You need to be able to index the ratchet blank (mount it on a shaft with a lathe change gear and improvide a detent if you don't have a rotary table). Use the sharp corner of an endmill, set so a line along one side of the mill goes through the centre point of the wheel to cut the teeth. If you mark the position of tooth 1, then index around to place 2, the correct depth of cut is such that it just erases the tooth 1 mark.
I've made a small ratchet wheel (3/8" diameter) this way in silver steel, and another 1 1/2" diameter in steel, both with no problems.
Neil