I've been using a first generation BOSE L1 for PA in my studio. It works very well and has a much smaller footprint than using either floor monitors, or a couple of mains. These days you should be able to get one for less than a grand.
You might also want to check out the Mackie 808s. A great self-contained 8 channel mixer/stereo power amp. 600 watts per channel and very flexible - you can use one power amp for mains and one for monitors. Or, you can run the power amps just for the mains in stereo and take a line out to a separate power amp for monitors. These days you can pick one up on eBay for less than $500.
Bill, tgo