Don't all Ebay purchases go through Paypal? I always thought it was odd that ecig stuff was restricted in the US, but not if someone bought from Ebay.
The other thing is that Kanger, Aspire and Innokin are going through another wave of enforcing MAP pricing and unauthorized sales. Even through China shops, Paypal is restricting payments to anything from those manufacturers as "unauthorized" and "counterfiet". I'm guessing Paypal is using a filter but that would tip off Ebay of unauthorized products. If so, that would prevent selling them under "dry herb atomizers" category too. I ran into this with fast tech trying to buy Kanger coils and Paypal wouldn't accept the transaction. I had to pay direct.
E-cig stuff is not really restricted in the US. Using them in certain locations is.