Startup idea: create a high quality camera gear buying and selling experience for the web, with many protections and conveniences built in. Selling your gear on Craigslist and meeting with random strangers at McDonald's and Starbucks is pretty much the only real alternative right now and gets old pretty fast.
This was an issue for music gear too, but somehow reverb.com managed to address it and make it a pretty painless experience. Their customer service is excellent, and if one of the two parties are unsatisfied, they'll intervene and try to find a compromise. They send you boxes to ship your gear in, they set up shipping for you, they automatically track the shipment as it gets picked up etc. I've been hoping to find something similar for camera gear, but have had no luck so far.
The only downside is that the prosumer camera equipment world seems to be rapidly shrinking, so it might be not a great idea to step into this space right now. Whereas there doesn't seem to be a dearth of people buying guitars, drum kit pieces and effects pedals.