I have a 1994 Plymouth Sundance and the radio acts up?

In my 1994 Plymouth for a week my radio works and then it goes out. Once it even worked when I turned the radio off by the knob. I really can't afford a new radio ( $130-$160 installed) So I am wondering what it could be or should i just save and have it done? Is this a SERIOUS problem or just something that Dodge has on all their cars?? Help LOL