I'm debating this same topic myself... My wife actually told me about the Toys 'R Us SP/Mario 3 special. I'm as indecisive as you about this.
The SP deal is a good one: $145 combo for $100. Future Shop lists the new DS at pre-order price at $199. But if I recall the US MSRP is $149. Which would make the Canadian equivalent likely $179. If that game with Mario64 or something, I'd jump on it.
I guess it comes down to whether the DS is worth the added $80. The only DS feature that looks good to me is the added bonus of Nintendo 64 ported games.
Is the GBA line going to be disappearing?