I responded to a Gumtree ad for a ML7.
I offered to collect and pay cash, seller replied they would deliver at no charge COD, I would be able to examine goods and pay only if satisfied.
Next day received email, apparently from well known carrier saying my goods were ready for delivery, I needed to go to a shop, buy a voucher for the cash amount and send a scan of it to them.
I didn't have a scanner so couldn't oblige.
Watch out for scammers, don't part with cash unless you can put your hands on the goods and the vendor at the same time.
DaveB