Tim's response here
made me think that elastic bands might be a training option for you.
Although I have to be honest - if at all possible, you should join a gym or Y, at least in the early part of your training. If you absolutely can't join because of finances, then so be it. But if you can afford to join but don't because you want to save some money, you might find it to be a false economy. Working out alone at home, besides being taxing to your motivation might also be dangerous if you start using heavy weights