No - there isn't a lens you can get that will work for both indoors and outdoors below the college level.
The next step up from the sigma is Canon's 70-300 which Mark mentioned ($560). It will focus faster than the sigma and it will be sharper. But it's still 5.6 so it still will be useless in low light.
The next step up from that is the sigma 100-300 f4 ($1000). Exceptional lens - and much higher quality than either 70-300 BUT it's still only f4 so it won't be usable under lights or in extremely overcast conditions.
Since you can't afford the sigma 70-200 2.8 there's no point in discussing options other than the two 70-300 lenses. Unfortunately sports shooting is expensive.
As to the 50mm and 85mm - first of all these lenses are only going to be useful for basketball not football. Just wanted to clear that up in case there was confusion (50mm is only good for about 15 feet and 85mm is only good for about 20-25 feet). Like Mark I have both but I never really use the 50 for sports anymore. It's good if you're directly under the basket but too short from most other places. The 85mm is too tight for right under the basket - typically you'll shoot from the corners of the baseline (or creep along the baseline toward the key if you want shots of players outside the arc along the other side). But, pay attention to those 15 and 20 foot limitations. Don't expect to cover the entire floor - or heck, even HALF the floor.