buyology
noun: The urge to consume, purchase, buy, own.
"He's so into buyology -- look at all those labels."
buyological relative
A mooching family-member who uses reverse-nepotism (i.e., instead of Person A's extending undeserved favors to Person B just because Person B is related to him, Person B pressures Person A to excessively favor him due to family ties) in an attempt to get you to purchase non-vital items for him.
Ethan Couch's parents were way too indulgent of him financially, and so he became a totally spoiled brat who expected ALL fellow humans to cater to his wishes, whether they were his buyological relatives or not.