Ok..I am looking to build a cement slab to put a barn on to store my mustang for the next 3 years while I am in germany....the dimensions of the slab are 12' x 16' and 4" thick. I will have some sort of wire reinforcement in the cement. it is the back yard of a house...ground will need leveled, etc.. WHAT IS A DECENT PRICE to have someone do this? It doesn't have to be perfect..just hold my car. Thanks!