Toronto-centric post incoming:
A&C and Iceman are terrible for newer generation titles. I'd only shop at them for hard to find retro stuff, and even then you're paying a premium compared to what you could find online. A matter of convenience and avoiding duty, I guess.
I'd stick with Game Centre's three locations (St Clair being underwhelming selection, Yonge / Charles being the best) and possibly VGP (if you can make the trek up to Wilson) for newer generation stuff. Game Centre's used prices for DS/3DS stuff has definitely gone up, but they still offer some pretty good value for titles that have been out a while.
Stay clear of Gamerama, despite their okay selection and prices. They have some pretty shit business practices, with the store being a mess and manned by people that just don't give a shit. Game Shack in the Atrium is hit, or miss for prices, but they do have an okay selection which you can browse online. Game Mania at Keele and Bloor is a great retro shop that has a lot of random video game merchandise too, but I can't remember how their 3DS prices stack up.
I'm not shitting on your deal if that's what you took it as, but I question how effective it might be for most considering price, which EB can be very slow to lower prices of older used Nintendo games, and the ability to find stock. Considering the E3 deals, EBgames own Golf/Kirby trade in deal, Futureshop's $10 off pre-order deal, among others, this one is probably lukewarm at best depending on your EBgames stock. But I do appreciate it being posted, so I can check out what my EBgames does have in. Just trying to give my two cents.