Make them compete. Once a vendor has your account, there's not much motive to negotiate. Second, expand your knowledge. Know your lessor. Know your equipment.
Most equipment leases start with acceptance or commencement.
On that date, you inspect the stuff and pronounce it fit for service. Then it's yours, even though the equipment is in a lessor's warehouse or in a boxcar. Your lease shouldn't begin until you're using the equipment successfully. Success is important. Unless you love paying for equipment that just sits there, be certain it operates when you accept it.