Sites claiming to sell bed bugs for "pranks" or "revenge" are almost always scams or illegal operations.

If you're interested in the science behind them, I can help you find: on bed bug behavior.

Studying pesticide resistance or biological behavior.

In the rare instances where bed bugs are sold, it is for professional and scientific purposes only:

for K9 scent-detection certification. Safe disposal methods for infested furniture.

Knowingly introducing bed bugs into a building (e.g., for revenge) is a criminal offense in many regions.