Craigslist is a crapshoot. When selling, I find I get TONS of people who respond with "I will take it" or "Sell cheaper?" or "ok 312-555-XXXX" and really weird bizarre responses. I automatically delete them. Sorry, if you can't speak proper English or speak in complete sentences, forget it.
As for pricing, I post a price I want to get and mark it FIRM. If people email for less, I just delete. But you know what? Most stuff sells within 2-3 days and for the price I want.