Thanks for all the help everyone! Lots of great suggestions!
I've been thrifting a lot with no luck so far (as was expected), and since I live in Albuquerque I don't quite have immediate access to some of the more frequently mentioned names (Brooks Brothers, Nordstroms, etc..), but I'm going to suck it up and start looking at some boy's sections this week. I don't have a lot of shame in this regard, so I'll let everyone know what I find!
Also, I had a friend with a phenomenally well-fitted suit recommend thick as thieves with an estimate of about 500 dollars for a solid suit. I hesitated initially, but I'm done growing, so I suppose I might as well?
Thanks again for all the great info! I'll be sure to report back with pictures/prices on what I end up with. If any of the rest of you are half as frustrated as I am, I hope this whole thread has alleviated that at least a bit.