There's a school of thought which goes along the path of there being a defined amount of work to be done and an expected time to do it in. Cheaper prices mean either the person carrying out the work is paid less, the premises overheads are lower, or some of the work isn't getting done.IE pay less, get less. I prefer to pay the minimum amount it takes to get a stamp in the service book and continue with completing the service work myself to to make sure that everything gets done ; since I am all too aware of the things which happen when bosses and share holders start making noises about "efficiency savings" (only doing half the job) and "streamlining" ( getting rid of some of the lower paid workers) whilst "maintaining standards" ( providing showroom comfy customer sofas and free coffees and biscuits ) and "putting the customer first" ( since it is the customers who the company must concentrate on fleecing) "improving quality assurance and governance" ( getting easily replaceable people to tick and sign boxes to say they have completed works--- even if they haven't been given the time and resources to do so).
"Pay less , get less" is a good rule of thumb but one which has to be combined with common sense and savvy.