Price mostly follows the footing's size, and size follows the ground and the load. Soft soil or a heavy load calls for a wider, deeper footing, and a longer run means more digging and more concrete. The schedule turns on the dig, setting the steel and the curing wait, which is the time concrete needs to harden before it carries weight. Your estimate puts the scope in writing so you can compare it with other bids.
Maybe you're here because an old footing moved, a wall cracked above it or a post sank. If so, I want to know why before we pour anything new. Usually it's ground that kept getting wet and drying out underneath, or a footing too small for what it held. Fixing the cause is what keeps the new one from going the same way.