Um, are you serious? This is the kind of thing that you should do your homework on BEFORE you sell. You can search on craigslist in your or other cities, as well as can search Buy It Now and completed auction listings on eBay to try to get an idea before you post your item for sale.
Not sure what the point of this thread is now, as what good is it going to do you after the fact to know if you got a good deal of not? For what it it's worth I'd say you got a good deal as I sold the same model for $600 on craigslist without a superdrive, and I knew I sold for less as I wanted to unload ASAP.
Hope this somehow makes you feel better. If you want us to help you evaluate your deals for any other items that you've already sold, just let us know.