Published guides put basic 4-inch flatwork in the mid single digits per square foot, shop slabs with thickened edges and anchor layouts above that, and engineered house foundations well above flatwork. On Blackland clay the pad preparation is a real share of the price. Written fixed quotes come from a free walkthrough.
More detail
Slab pricing separates into three tiers, and knowing which tier your project sits in explains most quotes. Basic flatwork (a patio, a storage pad, a simple carport slab at 4 inches with standard reinforcement) tracks the low end of published ranges. Shop and barndominium slabs price above that because they carry more: 5 to 6 inch thickness or thickened edges, deeper reinforcement, anchor bolts set to a building manufacturer's template, plumbing rough-ins on barndominiums, and tighter finish tolerances. Engineered residential foundations are their own tier: on expansive Blackland clay the standard house foundation here is an engineered slab, commonly post-tensioned or heavily grade-beamed, and the engineering, steel or cable, and deepened beams price accordingly. Across all three tiers, the ground moves the number: how much cut and fill the pad needs, whether select fill is imported over native clay, and how much moisture conditioning the soil demands before it will compact. A flat sandy lot near Whitesboro and a sloped black-clay lot outside Anna can carry very different pad budgets under the same building. The quote you should accept for any of it is written, itemized (pad, steel, concrete, finish, inspections), and fixed, produced after someone has walked the actual site, and that walkthrough is free.