Beyond the physical drivers of cost, a significant reason quotes differ is what each contractor actually includes in the scope. This is where the lowest number can become the most expensive choice.
Some contractors quote a low base inspection price and bill separately for tests that NFPA 25 actually requires, turning a seemingly cheap inspection into a series of add-on charges. Others quote a low number precisely because they do not perform the full required scope, leaving the building with an inspection that looks complete on paper but misses components a fire marshal will ask about. A transparent commercial fire inspection quote should make clear exactly what is covered and what, if anything, is billed separately.
The most reliable way to compare quotes is to compare scope, not just price. A slightly higher quote that covers the full NFPA 25 requirement is far less expensive than a low quote that leads to add-on fees, a failed inspection, or a compliance gap discovered later.