Jay,
I can certainly understand not wanting to waste resources. I wish there were a better way.
If you were in the Phoenix Metro I could help direct you. I would if I knew teachers in your area. It's a painful process, I drive several hours each way to get to my studio. I know others who have the same instructor that fly from Texas and California because he is good. Good instructors are rare.
If it would help, one of the ways you can cut down on the misery of looking is searching through competitions to see if any of the professionals in your desired style are in your area. It isn't a golden rule that they are good teachers.
I'm about to get screamed at for suggesting this because many here teach but don't compete and dislike this advice. You can, to a degree of certainty, know that these people do know what they are doing and can prove that they not only know current steps but can perform them competently. If you want to get more nit-picky check the Scholarship winners at the competitions to scope out their instructors. These people can obviously teach, because they aren't getting pat on the back wins for spending the most money.
I would look at the results in Emerald Ball, Ohio Star, the US Nationals and the Nevada Star Ball. See if any of these have winners who also teach in your area.
These are your best bet especially if you want to compete, but also many of these teachers know how to dial it down and teach without hounding you on technique.
Maybe this will help shorten your search...and for all of you out there about to smack me...I'm not saying that competing dancers are the only good teachers, I'm just saying it is one of the few ways to measure teachers in this art.