MacBook Pro resale value -- should I replace the battery?

Non-technical question here, sort of. I'm planning on selling my old MacBook Pro on Craigslist. It's in great physical condition, with the exception of the battery, which is nonfunctional. It's never been replaced, but after use and age it can no longer hold a charge.

Should I replace the battery before listing the laptop? That is to say, would the cost of cutting the price to list it "without battery" be greater than the cost to buy a new one? (Not to mention then I have to decide between a $20 hit-or-miss generic replacement or a $120 legit Apple battery.)

I think if the rest of the laptop is still in good condition, then replace it.

For one thing, it leaves a bit of a bad impression with a potential buyer. You're giving them a machine which works only with the plug and if they wants to use it on battery they'll have to go out and work it out with Apple himself. Personally I'd expect a pretty hefty price reduction for that.

If you replace it on the other hand, you can clearly state so in the description (eg "battery was recently replaced for $120 and should now allow you to work for a full X hours while not plugged in" or whatever) which actually increases the price and the value of the laptop.

I would not replace the battery, but simply make clear that it doesn't hold a charge.

Replace it. As someone who buys on Craigslist, I would pay more for a 100% product than a %75 product, and be quicker to buy.