I purchased a bag from Craigslist once. The lady who was selling it sold bags on both ebay and Craigslist and had a Paypal account and good ebay feedback. I paid via Paypal. She lived in another state so I just saw the pictures and she shipped it to me. No, I didn't negotiate because it was a bag I desperately wanted and the price was right.
I also purchased woodworking tools for my husband from Craigslist in a similar fashion. Paid via Paypal.
When buying from Craigslist there's more risk than buying from ebay because often you don't know much about the seller. But if you pay with Paypal the risk is less.
I've never bought a bag but I have sold bags through Craigslist. I always met my buyers in a public place and it was a cash transaction. I did do negotiating with the buyers. I have also been paid via paypal for non-local buyers and have sent the bags to their confirmed addresses.
I've bought a vintage Chanel and a LV pouchette- but both sellers first sent me extra pictures (which I then had authenticated on here) and we met in person in a neutral place so I could carefully inspect them to make sure they were the same bag that was it the pictures. I got great deals- $350 for an almost perfect Chanel, and $150 for a barely used pouchette.
I also bought a ring once, just because I liked it- and the woman swore up and down that it was worth WAYYYYY more than the $50 she was asking for it. Just for the heck of it, I had it appraised, and it appraised for $600!!! So sometimes, you can get great deals on Craigslist.