We own a concrete polishing company in the NYC area,
www.prep-crete.com so this is something we have some knowledge of.
Professional polishers use rather large grinding equipment that use successfully smaller and smaller diamonds, a mid-process densifying step, and then a stain blocker step which uses a high speed burnisher (not the grinder). A full polish to a #1500 is usually 7 steps, so 2,400 sq ft x 7 ends up being almost 17,000 ft which will take forever without the correct equipment. Most tool rental places also don't rent the proper diamond systems for this. Lastly, the grinders don't get close enough to the edges, hence the 7-8 step hand girding pads are needed for hand grinders, otherwise the edges look crappy. So between the grinding/polishing, edges, and burnisher three pieces of equipment are normally used by a pro.
There are some systems that claim to work a bit differently on floor buffers, but we have seen the results mixed on them as a floor buffer does not have much downward weight which is required to polish.
Recently there was a string about this on the GJ that may be worth looking into, but don't underestimate the time required if you DIY, and understand that DIY you would most likely not be doing the edges properly, nor burnishing in the stain blocker which gives the super shine.
A pro would charge in the $6-$8 range per sq foot. Most likely they would want 3 phase power which if not available in your building would need a large generator rental which adds to the cost.
Another option is to do a 'grind & seal' which gives the look of polishing but is only 2-3 steps and you then seal the floor with a good sealer. Gets the job done and gives a similar look.
