Guess I agree with the overall consensus.
And I think CRM is correct in reminding us that many people don't have jobs that allow them to surf and/or make calls at will. However I do disagree where some mentioned that it can be too much trouble to keep track. I'm talking about the serious potential buyers. They pm, say they want it and leave a number or ask how to pick it up. Those people I give 24 hours to pick up, usually. One day rarely makes a difference unless something's crashed and at that point you're probably not going to be able to pick and choose your buyer anyway.
So to recap;
First - Committed to buy, contact info left, agreed upon place to exchange within the next 24 hours (possibly longer).
I also expect courtesy from locals as a buyer and seller. Hopefully we're giving friends on here a better deal than CL or ebay with the expectation it will come full circle some day. I'm new to this board (not to the hobby) but I've seen this kind of generosity on here and other boards that really helps foster a supportive community.
If you can't wait to sell the item I would make sure to put in your posting, "First to bring cash gets the item, no holds!". However you have to realize that you'll run a lot of people off as they'll think they probably missed out and just won't call or pm.