My experience with Empire Flippers: A marketplace with huge asking prices entirely dependent on the greater fool theory.
I have my own review of their service coming up, but I think the quality you're gonna get from EF is infinitely higher than something you'd pick up off of flippa.
They're real businesses with real traffic, cashflow, etc. For as much as the startup world talks about starting a business from scratch, many would do well to pay for something that already has a foundation built for them.