A few years ago an earnest but out-of-it Dallas publication of the local city monthly magazine variety, trying to break into the "Best of" field (fat chance!), described the monthly Buchanan Markets show at Fair Park as the city's best "flea market." Oh, no, no, no. Flea market it is not. Buchanan's, held toward the end of every month, except during the State Fair, is a glorious bazaar where the discerning eye may discover true treasure. And maybe some junk. But not very much junk. No, this is a true antiques show--the best in Dallas. Check for dates at buchananmarkets.com. 9 a.m. to 6 p.m., Saturday (when it's being held); 11 a.m. to 4 p.m., Sunday. Three bucks a head for adults, kids under 12 free. Free parking and shuttle available.