But all else is rarely equal. When comparing prices I generally gravitate towards the higher end. Last summer we had a new heat pump installed. We got 4 bids for the job. $8K, $7K, $11K, and $13K. We chose the $11K, and price was certainly not the first deciding factor. We chose the company with the best products and service, and we would have paid $13K for that company to do the work.
It’s also not that simple for auto service. Do you want to go to the cheapest shop or the most expensive one? Which one will have the best quality? Look at it this way, going back to the original poster’s example. He needed a belt tensioner. He can go to the dealer, buy part #ABC123 for $100 and get a 12mo/12,000mi warranty with it. I use the same part, charge him $120, and give a 3/36 warranty on the job. Which is a better value?
Yes, we were often times more expensive than the dealer for the same work. Yes, we often got the job over the dealer.
I generally go with the middle estimate, to be honest, or the mid priced item if I’m purchasing something. The cheapest is lower quality. The highest, I’m wasting money or paying for a high end name. That’s my system, if I don’t know anything else about what I’m buying .
In this example, I’d go with the cheaper option, all else equal. Same part, same chance of failure. I never buy the “extended warranty”, which is basically what’s being sold for the extra $20. That being said, if I knew you or knew your shop and knew they did great work, etc., I wouldn’t be price shopping over 20 bucks.