Yeah thats true. I might just have to save up for it. I will be happier in the long run that way.
I would definitely say save up for Canon L glass in this case. I try to stick with L glass anyway purely because of the great weather-sealing (not really as important here, but when I'm in California I spend a lot of time on the beach and away from the house...and when it rains I have no chance of getting back to the house without getting soaked), but in this case it would be a good idea for you too.
For sports photography you need the ability to focus quickly. Since you're already somewhat hampered with using a Rebel body (in terms of focusing speed and accuracy) you want to fill the glass role with the absolute best and fastest-focusing lens possible. I have no problems with Tamron and Sigma (just sold a Tamron lens that I loved using), but they definitely will not focus as quickly as one of the Canon 70-200s. If you want to really be able to capture some of the better plays with precision...you're going to want to go Canon in this case.
On that note...I just purchased a 70-200 f/2.8L IS II to replace my f/4L. $2300 gone in an instant lol