I've been looking at synthetic grass. It runs from about $2.59 per square foot to $9.19. That is just the synthetic grass. Yes, I have watched the entire process. I estimate the cheaper grades will cost you possibly three times the above. Lot of labor, ground prep, a fine soft underlayment, landscape cloth, then the large roll of grass. I got the above prices from:
Synthetic Grass Price Guidelines
I will probably be going some type of sand, "crusher fine" which you see in many paths.
Rich