Anyone can quote you a low number on twenty laptops. The question is what happens in month seven when two of them fail.
Ask for the paperwork up front
A proper invoice with your company name, the warranty card, and the serial numbers recorded against your account. Without these, a warranty claim becomes an argument.
Standardise the models
Buying one model in quantity is cheaper to support than six different ones. Spare parts, images and training all get simpler.
Budget for the licences
Operating system and office licences are frequently left out of hardware quotes and then appear later as a surprise. Ask for them to be itemised in the same quotation.