went to my first swap meet in 1975. sold at my first swap meet probably around 1980. it would appear that what I always thought of as a simple process for both buyers and sellers is for some reason difficult for some.
here's my suggestion for you. put some random parts on the ground on your driveway. kneel down, pick one up and while holding up the item say, "how much for this?" maybe have you wife or one of your kids there to answer. repeat until you get the hang of it.
the same technique is good for both parts and complete bikes, except you will not need to kneel down and pick up a complete bike.
hope this helps.