No one on here is going to tell you to get something cheap. But you need to understand the source. These people look at this as their passion in life, and are willing to put in as much money as they have.
The truth of the matter is sports photography is very demanding on equipment. If you wanna see the biggest, fastest lenses, and biggest, fastest cameras, look at the sidelines of a sporting event. But, unless you are rich, you won't be able to get this sort of stuff. So I think the first lens you have mentioned is fine. You might want to try and get a 55-200 lens also, as they can be picked up rather inexpensively.
You can get more for more money, but unless you HAVE the money to spend on expensive lenses, they aren't going to do you much good. You may, however, find out that the lens you bought doesn't work very well. In that case, I'm afraid there's not much you can do other than spend a lot of money on an expensive lens like the ones aforementioned. But for the time being, go with your first idea and see what happens. You may find out you're very happy with the results.
We all have different standards of our own work, and the people who post on this forum's standards are very high cause they've been at it for so long. Its VERY possible for someone starting out that the results you get from your 30D and kit lens far exceed your skill level (right now). There's nothing wrong with that either, just start saving now cause once you get to a certain level photography becomes VERY expensive.