I usually sell in the spring and buy in January - right after Christmas when no-one has any money. At that time prices are at a low. You would be surprised how much of a difference the right timing can make and the best buys at this time are to be had from private sellers - if you are confident enough to buy privately. For dealers, the end of the month is also a key time for a bargain if sales have been slow.

If you are going for a new bike there are certain manufacturers that discourage their dealers from giving dicounts. BMW and Honda being prime examples. But even here you should be able to negotiate a few extras or some kit to be thrown in with the deal. Remeber, their cost price for these items is considerably less than than the retail so this is an attractive arrangement for both sides.