Some items are pretty standard. Such as many parts replacements. Telephone quotes can be made.
Other items should not be quoted without inspection; such as repairs, which require diagnostics, and installations.
The problem with many blind quotes is that they often get overbid, making sure to cover unforeseen contingencies, or underbid, not allowing for them.
Shops seldom if ever deliver the repair under the bid price when the job goes smoother than anticipated, and if the job is much more involved there is pressure to do the work in a less precise and detailed fashion, so as not to lose money on the underbid. To” cut corners”.
I recently had a call requesting a roof seal estimate over the phone. Such jobs can vary radically in labor times. In some cases the scraping and prep work is extensive, taking many hours, while in others only a light amount of prep work is necessary. In others the coach needs a new roof altogether, and a seal job can be done but is a waste of money.
My solution was to offer a free inspection, waiving the service call fee, and go over the roof and show the customer what needed to be done and why, with no obligation. And even to instruct him on how to do the job himself if he so chose.
While I cannot always offer this (as there is a net loss of time and expenses to do this on a mobile call) I like to keep this option open. It demonstrates my honesty and furthers my reputation as a fair and generous businessman, and even if the job is not gained after the bid, there is a good chance I will be the one called first in the future.
Beware of blanket bids, as they can often result in poor workmanship to save costs or overpayment for cases where the job is easier than the norm.