Repairing or replacing a concrete driveway
If the cracks are narrow and the slab still sits flat, sealing them or replacing one bad section can buy you time. When the driveway has sunk, tips water toward the house or has broken into loose pieces, the problem is usually the base, and patching the top won't reach it. That's when I'd tear it out and start over, because new concrete on a failed base settles the same way the old slab did.
What shapes the cost of a concrete driveway
Square footage sets most of it, then whether an old slab comes out first and how much digging the base needs. Heavier vehicles call for more reinforcement and sometimes a thicker slab, and a decorative finish costs more than a plain broom finish. If the budget is tight, I'd keep the money in the base and go plain on top, because the finish is what you see on day one but the base decides whether the driveway stays flat.