Quote - Always go with your preferred Company when the price difference is less than 10%

As a general rule of thumb, if the company you prefer to use for valid business reasons is Less than 10% more expensive than the cheapest bid, then always go with your prefered provider

this will always be more satisfactory and cheaper in the long run

The reasons for this could be.

1. better quality
2. the company will be around in the medium to long future to warranty and service you again
3. you've received good work and service in the past on a consistent basis
4. better follow up even when things go wrong
5. you trust your preferred company more

think about it. lets say the company you really want to use gives you a bid for $10,000 but the cheapest bid is $9,000

that is a difference of 9% , but if you go with the cheapest bid, you might find

1. the company over promises and under delivers
2. has way less experience and infrastructure than you're preferred vendor
3. takes way longer to complete the work than promised
4. gives you a lesser quality product that has to be replaced sooner than expected

after all YOU HAVE TO JUSTIFY when things go wrong!