My first AR was one exactly like this one, it was a 1983 also.
If I remember correctly, the MSRP was around $495 and the Colt 3X scope was about $125 more.
Mine was $425 and I didn't buy the scope.
Some people complain about the price of AR's today. I think they are a bargain when you understand that since 1983 the have on average only doubled in price today. Try the math with a gallon of gas or a loaf of bread.
To be honest I really haven't been following the current price on Colt SP1's. The carbines bring a bit more than the rifles, they cost more when new and they didn't make as many. This one is a later SP1 but still desirable to those that collect and shoot them. On an auction site such as the one I can't mention here you just don't know what it might bring. I saw one go for $1400 last winter, but two guys wanted it so they bid it up.
Local gun shop had one on the wall for over a year, they were asking $1299.00. I think it finally went for $1200 but it took a lot of people going through their doors for it to sell at that price. Most people would rather have a newer one.
Personally if it were mine I would ask around $1000, you can always go down if you have to. No hurry to sell, ask more.
Panic buying is in effect now, Obama gets booted that will slow or stop. If Obama wins...well let's not even think about that.