Duplo blocks (near Feasterville)

Hi everyone, I'm looking for Duplo blocks for my grandson -- these are the larger Lego blocks, about twice the size of regular-size Lego bricks. The holes on the top of Duplo bricks are open, as opposed to the closed holes of the smaller Lego bricks. Any brand of that size block will work (it doesn't have to be have to be Duplo brand). Any miscellaneous blocks or parts of sets are appreciated!