A supplier who wants your business long-term is one you can worry less about.
A vendor in a one-shot transaction can hide things from you. It is not his expectation to do repeat business with you, and he has no incentive to look out for your interest.
Very well put and very true:
On Tuesday I collected a vehicle that had a big problem (turbo blew) SIX months ago. To get the vehicle out of their rotten grasp, we had to pay 3 x times the quoted amount, as the turbo blew two more times while still with them. The legal route is a further waist of time and money.
Stay with who you know you can trust because they want to cover your back!!!