I have both bought and sold expensive items for at least ten years and it worked fine each time.
After we searched two years for the right RV, we heard a rumor that a certain one might be coming up for sale in our area. We googled the brand, model & year - there it was, listed on ebay, just a few miles from our house.
We researched a little more, called the number on the ebay listing for a test drive, inspected, put a deposit immediately, closed the deal a few days later. Two other buyers who had driven it called that afternoon ready to buy from him, but snoozed and lost. We've been 1000% satisfied.
The eBay points - research heavily...yes, inspect in person. Our RV had numerous bids about $20,000 less than it's value from people hoping for a steal, but the seller had a reserve price they did not meet.
Worked out very much like any other used vehicle purchase. Not sure, though, if I would travel a long distance for one. But I know others who have.