Decide the criteria before you see the prices
Write down what matters and roughly how much before any figures arrive. Scope coverage, staffing and supervision, evidence of insurance and screening, the fault-response arrangement, and price. Five headings is usually enough. Setting them in advance protects the process from the natural pull of the lowest number, and it gives you something concrete to point to when somebody asks why the cheapest option was not chosen.
Share the criteria with the bidders if you can. It costs you nothing and it improves the responses, because providers then address the things you actually care about instead of guessing. It also removes a common complaint after an unsuccessful bid, which is that the decision turned on something nobody had been told would be considered at all and had no opportunity to address during their proposal.
