The age of the concrete is a consideration as well as its condition, are there previous coatings?, are there glue and or paints on the surface needing removal? It comes down to hiring a company who "does this sort of work" and not one who can "do" this. Grinding off previous coatings averages $1psf with thick epoxy's requiring a $750 daily minimum. This being said, once the concrete is prepped, you are looking around $3.00 psf and up. This figure would represent a basic cleaning, 1-2 coats of stain, and 1-2 coats of sealer. Your floor (depending on condition) may also need an overlay which also can add $1-2 psf ahead of any staining. Its all about proper prep for it to last. If you would like more information, feel free to give me a call to discuss your specifics. No charge for hometalk members!