If I buy the Nikon D90 can I trade the kit lenses for a better one?

Also where could I trade it in? I live in Vancouver.

No such thing as trades, unless you lose in the process. Like your lens & $100… They have to make a profit when they resell the lens. And legally, it can't be sold as a new lens…

Ah, you're already so good that you can push the 18-105 or 18-55 to it's limits? Impressive!
An 18-55 I'd keep in case you ever need a cheap lens on your camera, an 18-105 is easily sold.

Store-wise, you can't trade lenses in that fashion. A good alternative though would be to sell the lens and use the money to buy another, or go on online forums and use the forum marketplace to trade your lens. Contrary to popular belief, it's a pretty safe environment. Most of my equipment (~$2, 200 total) was either traded or bought used on Photography on the Net.

Larger camera stores offer the D90 with a variety of lens kits - or if you don't like any of the combinations, they sell the D90 "body only" (CAD 780 at http://www.henrys.ca ). This way you can buy the lens(es) you really want separately.