By the looks if it is a dreadnought ( why does that rule it out btw?)
I found one new online at £759 with a case.
It looks nice, has a solid spruce top, worth is very much dependant on how it plays and what its condition is.
You can pick up some bargains on ebay if you take your time and £500 gets a lot of guitar, i was really lucky and got a guy to end an auction early, for a mahogany martin for £500, i could probably sell for a lot more….
Make sure you go pick it up though, i had an ibanez 12string delivered today the seller wrapped it in one bit of bubble wrap and sellotape!!!
Its fine but its a miracle.