C.F.
try some of the department stores like nordstrom's or neimans. little heiress has a small boy's section, but maybe worth the look. janie & jack has a pretty good selection. also, there are a ton of children and baby boutiques in north park. one of my favorites is Peek. i have a girl, so can't speak to their boy's section (and i haven's shopped for a boy's gift here, unlike the other places i mentioned) but they have great clothes.
good luck!
ETA: oh yeah! and u might also want to try consignment stores like cutie patootie in frisco, or kid2kid.