fit lifter
A fit lifter is a person who visits a retail store in person in order to try on merchandise, ie, shoes, pants, shirts, only to determine the correct size. No purchase will be made at the store. Rather this customer will subsequently purchase the item at a lower price online.
Joe went to the shoe store to try on some Vans. He found out that size 11 fit great. Then he ended up buying them online for $30 less. Well done you fit lifter!