Check out the link on our website for Universal Medical Systems. They carry their own line of ultrasounds, but also take in old ultrasounds on trade, so have a large variety of different machines. They will warranty them and as they “build” their own probes, they can replace/repair the probes on most machines. They also give GREAT customer support, so well worth contacting them and seeing what they have.
We currently have two of their machines and have used a variety of different machines. Most are fairly easy to operate and work very similarly. So, there isn’t that much of a difference from machine to machine. One thing that we “have” seen is that the resolution on some of the cheap machines you see on ebay is horrible by comparison.
With regards to learning to do it yourself, it is recommended that you have at least 100 guided ultrasounds/palpations before you will be reasonably competent. Flip side of that coin is that most vets when they come out of vet school, unless they have taken a rotation through equine reproduction, have had their hand in less than 10 mares <sad sigh>. Frustrating. Those vets that have been doing it for years and can palpate blindfolded and in their sleep are a Godsend. But, some of the students that come out of school and set up shop scare the pants off of me. They just don’t have the skill or training necessary!
Most states will allow you to ultrasound and palpate your own animals with no restrictions. Palpating and ultrasounding outside horses will depend on the state, as well as what exactly you are doing. Fine line, but it is a distinct one.
In any event, if you go: http://www.equine-reproduction.com/index.shtml and follow the link for Universal, it will take you to their website. Their prices are competitive and they are truly really, really good to work with!
Hope that helps!