I've looked, but when I do see it's being staged, it's always followed by the revelation that it's being done by a poor-quality community theater,

Well... so is 90% of the Shakespeare out there. In fact, 90% of the theater out there is poor-quality community theater. Of the remaining 10% about 8% is good community theater, and the last bit is professional theater (of varying quality).

I'll leave it as an excercise for the reader to put the various SCA productions into the appropriate categories.