Though I agree with you, and prefer running in stereo, if budget is a concern, I'd suggest purchasing one SINGLE 'higher quality' more expensive speaker PA such as the Mackie SM450 or EV SxA100 first (instead of going with 2 lower quality stereo PA speakers), and then later on, when your budget permits, purchase a second PA speaker (SM450 or EV SxA100) to run in stereo. I believe that the 'audio quality' itself supercedes the requirement for stereo, though I admit that running stereo further enhances the sound & ambience. Just my opinion of course.

By the way, my PA setup consists of two EV SxA100s. For the smaller gigs I just take ONE PA speaker running (running mono) and it sounds pretty good. I take both SxA100's and run stereo for the larger venues. I'm really happy with my setup PA setup cuz it's both lightweight & portable and offers terrific sound. - Scott