Depends how long you're willing to wait to find the right buyer. I find that a lot of sellers are just looking to unload quickly because they need the cash. I wouldn't buy anything on Craigslist for less than 1/3 off the typical going rate from Apple.
To be honest, whoever bought your 2009 MBP for $1000 is the real sucker. The mid-2010 model can be had at MicroCenter for $1000 + tax (if your state has sales tax).
I have sold many things on Craigslist. The only item that didn't move for the price I wanted is my current Samsung 61" DLP LED projection - but that's because of the mad rush for LCDs. Everything else has sold quickly. Every Apple product I have listed (2 iPads, three MacBook Pros, one MacBook Air) has sold within one day of my listing it, most same day, and I never undercut Apple products nor do I negotiate lower prices. The last iPad I sold had 10 emails within minutes of my posting - and I had it up for $450. Mind you, it's the 16GB version, which can be had for just over $500.
Like I said though, it's all about how you write your ad.
Speaking of your MicroCenter ad, you must not be in the know about how California works. A damn near 10% sales tax is plenty incentive for people to avoid buying from stores wherever and whenever possible. Also a lot of folks don't want to wait for shipping, and they want to get hands on it and make sure it works the way they expect before buying it so they don't end up with a lemon.