i like this shot a lot. i wish the wrestlers filled the frame a little more, but there are nice lines and its a good moment of action.

Hey, took a quick look through your sports stuff. You've got a good start in that you've gotten faces. Faces will make or break a sports photo. So will backgrounds, and unfortunately the backgrounds in your photos break yours. The only part that's your fault is your positioning and framing. Try to either get a higher view point to take out the stands and people walking around, or get low and zoom in tight. The parts that aren't your fault look like they're your equipment's fault. What body and lens are you shooting with? Also are you using the pop up flash on the camera? If you are, don't. It'll ruin the image. If you can't afford a hot shoe flash, just crank your ISO as high as it'll go and practice using the the reduce noise filter in photoshop.
The truth is that sports photography is damn expensive. I've got what would be considered a medium level setup. I shoot with a Canon 20D and a 70-200mm f/2.8 telephoto lens and a 24-70mm 2.8 lens if I can get a hold of one to borrow. f/2.8 fixed lenses are pretty key, you'll be able to shoot in those nasty low light gymnasiums a lot easier. But that setup ran me a good $2000. But if you can make money off your photos it'll eventually pay itself off....eventually. Ok I've rambled off a lot, but let me know if you have any other questions.