I bought my computer about 6 monthes,and because I took it from one of my friend,so he gave me the lowest price.But also it costs me about $400,so I think that your computer could valued by this price.
Mine cost me about 1300 dollars, less than 2 years ago. I could bye the same computer now for less than 400$. But it's still good, and I wouldn't change it.
i got my computer in 2003 and it cost me $1000 and still i think it was expensive compared to the prices today. i can't upgrade my compueter since i have to change the whole motherboard which buying a new computer would be better