Another TIP...
When considering a private-party purchase, I ask the seller to provide the items SERIAL NUMBER, when applicable.
Scammers hate this question because it allows potential buyers to verify the item is REAL, and usually, what retailer the item was originally shipped to for sale.
I always call the manufacturer and/or the retailer to confirm the item's identity. As a bonus, the manufacturer usually tells me which, if any, upgrades are appropriate.
Just this week, a I was looking at a potential upgrade. The seller refused to forward the preamp's serial number. He also insisted that payment be via direct deposit. Bothe are Red Flags for me...
I hope this this is useful...