If you haven't been to Mile High Flea Market — or the Flea at Mile High Marketplace, as it calls itself — lately, then you're missing out on some prime people-watching, headed up by guys with cut-off T-shirts and ponytails guzzling beers alongside Rascal-riding grandmas hunting for deals. But the next-best reason to go might be the piles of electronics available for purchase on the market's far west side. A vintage 1970s Kenwood receiver for $20? A pair of waist-high Technics speakers for $40? These deals are hot. Just don't forget to ask the "salesman" to plug in your pick to make sure it works.