Powdered laundry detergent in hot water. 1 spoonful in 2-3 liters is fine. I also add Oxi-clean or Biz.
Soak for an hour or less and rinse well.
Toss them onto a towel to air-dry in a couple of hours, or shake each one by hand to dry in 10-20 minutes.
Cheap, fast, leaves them feeling squeaky-clean.
Use alcohol or pencil eraser for stubborn spots.
Never use heat unless you are sure they are all PBT.