Macbook Pro from 2009

What is a reasonable price to sell on Kijiji (or Craigslist)? It's a 2009 Macbook Pro 13" 2.16 Ghz Core 2 Duo. It has 16 Gb of memory last time I checked and a 500 gb hard drive. I know this is for sub section is for buying, but I need advice and there isn't a place for this on the forum. It's in fairly good condition. The screen isn't cracked, there is the odd dent.

My sister is getting a new rMBP for christmas, I get the old one to do with what I please. I am looking into selling it but don't know how much it would be worth. I either want to sell it, or do a crazy mod on it like the Modbook Pro. But that is really expensive, and unrealistic in my view. They also don't do this with anything below 2011 MBP's.