1970 Duster Average Price? ?

What is the average price for a 1970 Duster? I'm not talking about a really nice, recently redone car, but one in drivable condition that needs just a little work. I've been looking online at prices and they vary greatly, so I want to make sure I'm not paying too much or too little. And also, if anyone knows how much the Duster cost when it originally came out, it would be appreciated.