Yes, there are some decent $5k boats out there that can be had for sailing not too far from shore. But a $5k boat for sailing around the world....hope your life insurance is paid up. When you really start looking into boats, you will find that boats built for blue water (middle of the ocean) sailing, come with a much higher price tag and there are reasons for it.
I've heard of people making similar journeys in even smaller craft. I was also looking at more of a coastal route because of that exact reason... Is that feasible? Up the west coast to Alaska and from there Russia and Japan? Or is it not quite that simple?