The other thing you need to think about is if anything should ever happen to your bike - you may have some issue with insurance. If you drop the value in purchase, then you may be up a creek trying to re-coop funds for an accident/stolen bike.
Personally - I don't get it, it's like paying tax at a yard sale. But I've bought two used bikes and paid the stupid tax. Cash Grab I say!
I wouldn't worry about that. Don't lowball the value when the insurance company asks you what its worth or what you paid trying to keep your premiums low. That may f*** ya, but I've found that providing 3-4 kijiji or autotrader ads of similar make/model/mileage will always get you to an adequate replacement value.