Aj is correct, manufactures do not just put in a door switch so they can charge you extra for the dishwasher, it's a safety device.
Believe me if the manufacture could make a dishwasher without a door switch so they could sell it cheaper they would.
Door switches are cheap, maybe you looked up the door switch for your model dishwasher on the sears site and thought the price was to high, but if you post your model number here we can do some research on it.
Sometimes you do not have to replace the door switch assembly, but just the switch itself.
Also I think you will find appliancepartspros
maybe cheap then sears, even for sears parts.