Alaskan
Herd Master
Good pointsSomeone I know had good success with it with her pigs, I've heard mixed things for sheep. For $500 I'd just save up a bit more and get a cheap ultrasound scanner (can be found for ~$800) and learn to use it. At least with that you can do fetal counts and measurements.
Personally, I'd learn to draw blood and send in for pregnancy tests on a small flock over a preg-tone. Red top tubes are something like $0.40 each, it takes maybe a minute to grab a ewe and pull blood once you know how, testing is $3 each at the place I use, and shipping cost me about $5 this past time. The preg-tone doesn't allow you to test any sooner than blood testing, requires just as much handling, and is less accurate. Someday I really want an ultrasound just for fun though!