Whirlpool WP8520839 Collector W/Check Valve OEM Part

Installed new Collector W/check Valve on the bottom of the dishwasher tub. About a 30 minute job (including removing the dishwasher from the cabinets--water supply, drain, and power--and reinstalling it. It would be nice if the manufacturer supplied the rubber check valve separately--small piece of rubber about the size of a nickel, probably $1 to $2--instead of selling it only as part of a $38 assembly.