The receiver is about 3 years old now and would have cost you about £800 when new. The thing about the RXA8xx models is that they aren't all that different from the RXV6xx model and doesn't include the better DACs or processing power you'd get with the models above it. What you are basically getting is a better build and superior chassis. You can buy an RXV685 for under£450 and this would include a manufacturers warranty.
You also have to take into consideration that the A860's current incarnation, the A880 can be had for just £750.