A very good store is Max Sports, they are my number 1 store. Good prices, excelent stringing, amazing service.
depeding on where you live.. theres lots of places. there always yo's at first markham places, extremely good quality stringing, but the prices are marked up quite a bit.. (comparing to racket prices in hk of course). theres also a place at midland and sheppard... (winningbadminton.com) There is also of course the badminton clubs, mandarin, lee's, and flying dragon..