There were 3 types 一元店 in 渥太华. The red color name one is best, more items there but closed earlier this year. The green color name "Dollarama Store" is big and Ok, But they started sale as $1.25 to $2 for the used $1 items recently. There is another red color store, call "Bulk or Two" store, they have less items but some are different from Green Dollar store.
You can find this store in or near most shopping centers.