Yes, sadly there have been quite a few.
- TransferBuy did an exit scam
- CityGoBuy did an exit scam
- Ytaopal did an exit scam after many years
- Ufobuy has fake shipping estimates and other shady practices (video)
These are just suspicions, when an agent does an exit scam you never hear the whole story, obviously.
If you got scammed by one of these agents, try to get a chargeback from Paypal or your credit card company.