Sugar Twin comes in a box of 40 packets for $1 at the dollar store. Wal-Mart sells Sweet 'n Low in boxes of 100 packets for $2.25 and you can get 800 packets of Equal at Costco for $16.84. Compare the costs: .025 cents at the dollar store, .023 cents at Wal-Mart and .021 cents at Costco. Not huge savings but every little bit helps, and if you prefer one of the bigger brands, you'll want to head to one of the big superstores.
Dollar stores are known for having mostly off-brand merchandise. This can be a good thing and a bad thing. It's good if the quality is comparable to a name-brand but costs a lot less and it's bad when you end up throwing something out because it's terrible. A bargain is only a bargain if you're getting quality for the money. My motto is: try it once and if you like it, buy it again, if you don't, you're only out $1 and now know to avoid that product.