Cheapest is not always the best.
I have run quite a big business and when I needed a subby in or work doing, the quote was only part of the process.
How they conducted themselves on the phone- are they pleasant or answer just ello no company name.
When they visit, are they on time, are they smart and presentable, do they have examples of previous work, do they have insurance
It all builds a picture,
People do not always want cheap, certainly business to business, if the job is cheap and turns out crap, the person who gave the work out will look a right charlie.
You need to sell your benifits, but not just on price or you'll end up a busy fool