I can guarantee it is a scam and that you would lose your moneyThey will have also written to anyone else who bid on the guitar over a certain value
There must be crooks who watch ebay sales ending just waiting to send out very realistic looking emails that look like they came from ebay
I would forward the email you got to ebay's fraud dept
spoof@ebay.co.ukI do wish that there was a way to hit back at the scum who do this sort of thing