acid stained concrete
Yessir, you were right to ask for a pros take on this; I don't think the DIY approach to thin stained concrete applications is the answer that will give you the best results for the $$$.
Acid staining concrete depends largely on the concrete underneath the stain; our procedure makes sure that the substrate is 100% able to accept acid-staining and therefore really clean the surface, involving powerwashing the floor (where feasible), floor machines perhaps, then etch it with acid, neutraize that acid - then rinse before we do anything. You should not overlook this important step nor accept work from someone who does.
Then there may be needed an application of a skim coat of a polymer-modified concrete product to a thickness of about 1/8", very thin, let dry.
If not, then the application of the stain can proceed; this is where the artist comes in and creates a unique pattern on your floor. Once applied the stain is neutralised and let to dry. Then 2 coats of sealer is put on top, could be epoxy or something equivalent but it must be hard enough to prevent wear and tear
You will be looking at something around $4-6 per sqft depending on size and other details, but expect it to take 2 days for a good job. A good crew can do 2000 sqft in a day but the time is about the same.