But the rule in California is, a person can have only so-many yard sales per year (maybe 4), anything more frequent (such as every weekend, which I have often seen), requires a sales tax and business license. I'm not sayin' folks don't get away with such stuff.

I'm not sure of the legal issues where, say, we agree in California that you will pay me $5 for a certain chip and that we'll meet in Nevada (coincidentally the bourse at South Point) to complete this transaction. I know it becomes infinitely more amusing if O. J. Simpson rushes in and grabs the chip!