I came across something rather similarly suspicious on london gumtree a while back, I sent an email asking about an attractively-priced rivera amp and got this in reply...
"Hello,
The Guitar Amplifier Rivera Venus 6 Koa Cabinet Rare is still available. The price I would like to obtain for it is £800. The guitar comes with all accessories and full warranty.
Right now I'm located in Manchester with my work. If you are interested to buy it now, I will do this transaction only through eBay in order to have a safe transaction for both of us. To start the transaction please reply me with your full shipping name, address and your eBay ID.
As soon as I have them I will start the official procedure, and eBay will notify you about this. eBay will send you an invoice with all the info you will need to complete the transaction. I will handle the shipping to your location, so this will be free of charge for you.
You will get the guitar and you will have 3 days of inspection in which you can decide if you keep it or not. In case the item is not as described and you don't want to keep it, you notify eBay and you send it back on my cost! If you want to keep it, you notify eBay. Payment method and all the details will be set up by eBay for security reasons. They will contact you to confirm the transaction by email. You will get the item in max. 48 hours.
I'll be waiting for your reply soon with the requested details."
I was surprized his uncle hadn't also recently passed away leaving a large sum in his bank account.....