I was trying a few powered speakers in Tom Lee Music a few weeks ago and I really liked the Yamaha MRS line. There's a less expensive brands like Behringer that sound good but I am a Yamaha fan because there stuff has lasted me forever.
http://www.sweetwater.com/store/detail/MSR400/ I like 12" speakers for most of the live sound I do, I supplement with a 18" sub. But even the 10" and 8" versions sounded pretty good, Just the low end was not punchy enough for me, so therefore 12" is perfect. 15" is just to damn heavy for me now...and I have the sub on wheels.
These are accurate enough to use in a studio.
You could buy just one if it's just to be a personal monitor. Buy a second one later.
If you spend a little more the DXR series have a 3 channel mixer so you can use it as a stand alone solo gig PA.