iPod Prices in Canada going up

When I bought my first iPod 3G 15GB back in January I spent $561.20 that includes 15GB model, 2 year warranty, and 15% tax. I love it, but know with the new 4G iPod you get a 20GB Model costs $429Canadian, plus you need to buy the new belt clip case( Looks the same to me), Dock ,and a new warranty. I don't know were I'm going to put this new Dock. My Dad who we bought a iPod for Fathers Day needs his Dock. Anyway its just unfare there asking me to buy all this over again the thing is basically the same shape. It's going to cost me $708.40 including tax to buy a 20GB and all that stuff over again. So I'm asking if I can use my old 3G dock and 3G case wiht this new 4G iPod?

I don't want a 40GB. All money in Canadian Dollars

Tank-you so much
Gamer