Good luck with the sale OP!
I agree. While I'm not here to scam anyone it's always best to take caution when buying any hw wallet. Ledger stands behind its security to where you can verify the device with their app (iirc they shipped their products without a security tape on the box for this very reason). For trezor (and possibly keepkey) there are ways to validate their authenticity. Furthermore, no real hw wallet will ship with a seed included. You always want to generate your own seed (and make a second one to make sure that the rng wasn't tampered with).
Why buy a device from strangers when you can buy from the official site. It is safer. I have no complaints against the seller, but I would only buy from the official manufacturer directly.
I bought this device simply for a test device, since I am working with a company producing hardware wallet solutions.