I would try to figure out why all the fish died before going to get more.
What size tank? 10g.. Ok what kind of filter, heater, gravel and decorations? Were they cleaned? If so, what were they cleaned in?
What I advise you do is clean everything in the 10g with hot water and a mild watered down solution with plain white vinegar and rinse it very well. Throw out the filter cartridge and get a new one without carbon, fill the tank and let it run for a few days without fish in it. Beneficial bacteria can only grow if you add a fish so you'll have to put some fish in then, DO NOT add a pile of new fish at once. One fish, 2 at most, will suffice for the fist 2 weeks or so. This will allow the water chemistry to balance. Then you can add a couple more fish and wait a few weeks and then add more. Until you're at your max for a 10 gallon.
What I think you did was plunk in a pile of new fish without ever putting them in quarentine (which means putting them in a small tank before introducing them to your community tank to see if there are any illnesses from the store). Water chemistry is a very sensitive thing in a closed environment like an aquarium.
Don't go get two more 1 gallon bowls. You can do better for your bettas.