You can also try looking on the Easy Care Inc site (makers of Easy boots) as they have a list of trimmers. It's basically a natrual trimmers classified ad, they aren't necessarily trained, but you can at least get some names and ask some questions and find someone in your area.
I think knowing what a good natural trim looks like is a good idea, so you don't get taken advantage of by some yahoo wanna-be. The internet and forums like this can really help you learn a lot about it. However, I don't recommend just reading some online help and trimming on your own without some hands-on. You can seriously mess up your horse's soundness. If you go the route of "do-it-yourself" please get some training first! Sometimes just picking up some nippers works out, but usually it doesn't.
So when you find someone, ask the right questions, what sort of training have they had-how much experience do they have and can they give references? Also, I think if a person does a barefoot trim but still does shoeing, as well, you won't get as good of a natural trim from them than from someone that does natural exclusively. Seems if you have shoes in the truck, it's easier to resort to that than to really think about the trim, plus shoeing can be more lucrative-a farrier makes more off shoes than trimming alone. (that's not saying they are just out to rip you off, either!!! Most farriers do want to help a horse out with everything they know, they just aren't up to date on the new techniques and are afraid to try it until they know it works and feel confident to learn it all over again)