I'm not an economics major, but the Canadian dollar has dropped VERY quickly, and the prices haven't had a chance to adjust yet. For Americans, this is THE best time I've seen, possibly in my entire life, to do some cross border shopping.
That said, the Waterloo Regional has got to be some of the best bang for your buck around for US teams. 25% more purchasing power (prices here are about the same face-value CDN vs. US), combined with the fact that it is a small regional make this a GREAT sell. You're paying less for an excellent team to award/qualifier ratios, and a large number of matches, that is of course if things like that are a priority to you or your team
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On top of that, Waterloo is an extremely well run event, and although it isn't as big as the GTR, I would definitely argue that gameplay at Waterloo is a much more fulfilling experience.
Can't wait!