How do you compare vendors fairly when they offer different services?

Define your core need first
Write down what you actually need solved. If you're hiring a painter, is the core need basic wall coverage or expert color consulting? This focus helps you see past surface differences. Separate nice-to-haves from must-haves.
Create a weighted scorecard
List evaluation criteria: price, timeline, warranty, communication style, experience with your specific situation. Assign each category a weight that matches your priorities. If timeline is critical, weight it heavily. Then rate each vendor 1-5 on each criterion and multiply by the weight.
Account for trade-offs
A cheaper vendor might have longer waits. An expensive one might include perks you don't need. Write down what you're gaining and losing with each choice. This makes trade-offs explicit and helps you decide if the premium is worth it to you.
Clarify apples-to-apples comparison
If vendors offer different scopes, ask each one: "What's included in this price?" Request itemized quotes so you can see exactly what differentiates them. Some include add-ons, others charge extra.
Trust your gut on communication
If a vendor is unresponsive during the comparison phase, that's predictive of their service later. The cheapest option means nothing if you can't reach them when problems occur.