| As others have said it's all down to how it's been looked after. If you ensure it's warmed properly before riding (allow 90+ secs before revving), then it should be less likely that you'll hit rocker problems, some have had many need replacing, others have had none.
I would say it should be worth more than 5K, if you can get it for 5K then it's either a bargin or there's something seriously wrong with it.
My 748e with 6500 miles on it was £4750. Really depends on condition as well. | 
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