Matt,
I think that is pretty high for the original sticker. I looked up my 1972 Blazer and it came up as $3253 as the sticker. It listed 4 wheel drive as the only option though. Back then the top was even listed as an option.
My guess is that it is closer to $4000-$4200. You can look yours up at this link.
http://www.nadaguides.com/home.aspx?...=28&p=0&f=5000
Click classic car, then trucks/SUV and then your information that they ask for. When it gives you a current value, just look at the top and the MSRP is listed there.