Number of things I think -

Location - Fuels so expensive and a bike couriers a joke (price wise) if you dont have a van.
Originality - Non original items can almost half the value.
Seller - As mentioned above a shop you can take it back too when it seizes up a week later is piece of mind to some people.

I sold mine last year November for £3000 non original but it was for sale for 3 months almost and the guy that bought it really wanted it even though it was heavily modified. The shops have the advantage of sticking them on their website and just waiting for the right person to either spot it or walk in. I guess what im saying is advertise it for as long as you can for as little as you can and eventually you'll get a fair price.

My two-penneth worth...

Jim
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"............should have bought a Honda"