They may be too young for Hershey bars, but they're old enough to get dressed up. Infant Halloween costumes have grown more and more elaborate. Need help sorting the tasteful from the tacky? Old Navy's two-piece fleece dragon ($19.50; oldnavy.com ) is soft and easy to crawl in. Babystyle's fuzzy Fly the Coop Chick ($19.99) and its golden Go Fish bunting ($24), both at babystyle.com , are among the most beautifully designed, though sizes run large. PsychoBaby's black pumpkin tutu-and-hat set ($30; psychobabyonline. com ) is cute, not prissy. But buy now; kids' costumes sell out before you can say "trick or treat."