Well depending on the disability you could always wash a few neighbours cars for cash,
Although that might take some time to raise the money for a tv.
I myself am physically disabled so i can understand about hard work, but doing a few odd jobs for the family and neighbours should be ok,
Also if you get an allowance from your parents save it and be as tight fisted as possible.
You might have some stuff around your house you no longer use so you could flog it in the local newspaper.