It's easy to think so, but cheapest isn't always best. When comparing estimates, here are just some of the things you should think about:
Is the contractor registered and insured? By law this is protection you're entitled to and contractor status can be easily checked at the Attorney General's website.
What kind of equipment does the contractor have? How will it access your property? Is there the possibility of damage to your lawn or landscape due to the weight of the machinery or potential hydraulic fluid leaks?
Has the contractor shared what kind of safety provisions will be taken to protect your property and the surrounding area? Think about your home's siding and windows, nearby landscaping and fragile plants, as well as vehicles and pedestrians.
Be sure to read and fully understand your estimates. If the facts aren't in writing, you have no guarantee of getting what you want. Will the stump be ground deep enough for your future plans? Will excess debris be taken away or left behind for you to manage? If you have significant roots associated with your stump, are you sure they'll also be fully removed?
The principle of "Buyer Beware" applies to many things, including stump removal. Take the extra steps to be an educated consumer and learn exactly what you're getting for your hard-earned money.