Value of a SOB - XJ600 Diversion

A colleague who is about to take his test has found what seems to be a
reasonably priced post DAS bike. Currently has just under 4K on the
clock although it's 12/13 years old, in pretty good nick apart from a
couple of dinks on the tank where something fell on it in the owner's
garage. Seems to sound sweet enough, the exhausts are in good nick
which I believe is a weak point. Tyres look OK but they're the
original cast concrete yokohamas so I'd change them.

So what's it worth?

 

I paid £1200 for mine (20k, 4 owners, mint condition and a personal
plate)

My Dad paid £700 ish off ebay (18K, topbox, snotoiler)

Both the Diversions in the house run on BT45s. The exhausts are a weak
point at the collector boxes, if the bike has a Motad exhaust like one
of our Diversions it sounds like a sewing machine, quiet as a mouse.