Yea it is definitely possible to make a profit in the bazaar just by buying from PC's and selling to NPC's. I tried this for a while but made a minimal profit (maybe 200-300pp/hour max) and it takes a lot of time and effort to do. The only other way to get profit in the bazaar takes much longer (i.e...

I have done it before so it can be done. However with 2 windows up it ran much slower for me, probably about 70% of normal speed.