A sealer bought from a hardware shop is only one part of the cost of treating a concrete driveway. A site quote may also cover degreasing, moss removal, crack repairs, edge protection, masking, equipment, application and a return visit.
The final price reflects the area, the condition of the concrete, access and the finish required.
A large, clean driveway can be straightforward, while a smaller surface beside garden beds may need slower preparation. Comparing only the price of the product can therefore give a misleading picture of the work involved.