No idle hammer in mine at 27k but the clutch makes a racket in or out. I also have the clutch vibration from 2000 to 3200rpm which can make the clocks shake about and the handlebar ends. Maybe this is what you've been feeling.
It is annoying but not enough yet for me to spend money!
I have no service history either but apart from oil and filter, one air filter and set of plugs it's not needed anything as yet.
I'd not pay 6k thou, I only get offered 4k trade in on mine, if they even want it, try 5k or there abouts, high mileage ones are not popular!