I just got this in september, wasn't refurbished or anything. 13" non-retina, 500GB, basically the base model. I'll see if it can help finance an upgrade.
As a starting point, you can check Mac2Sell, eBay (including completed sales), and Amazon for prices of similar models, to get an idea of what a reasonable price may be. Then adjust the price to account for condition, configuration, remaining AppleCare coverage (if any), etc. You can also check the Apple refurbished store to see what similar models are selling for.
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