My back hurts, what kinda chair can i buy to make it better?

i know work causes some of my back pain because i stand and bend over all day, but even after sleeping or resting for hours my back hurts even more. the chai i sit on at home is a camping chair so i know its no good for my back. what kinda chair can i buy for watching tv, and sitting at my computer desk? i m poor so it cant be over 50 dollars, but i want to find a cahir that will help or at least not add to my back pain.