It's funny how many people would email this: "Interested, pls txt 555-5555"
I ended up switching to Close5 and had a lot more luck with that - even near the end where I was just giving stuff away. For some reason people on craigslist were still way too picky about free stuff, one guy even asking if I would pay for it to be delivered.
With all of these services, I've found the biggest problem to be with people not knowing how to read. If you say firm price and pick up only, they'll still try to get you to deliver and go down in price.