You cannot keep any fish in bowls, since they curve inwards at the top, it doesn't allow for much oxygen to circulate in and around the water. There are few cold water fish you can keep in a small tank.
If you would like a Goldfish, I warn you that you will need quite a large tank. Goldfish don't need heaters, but they do need filters - as do most fish.
If you do not buy a filter, you are going to be having to clean your tank out a whole lot more than if you have a filter.
I suggest getting two Fancy Goldfish and a 40 gallon tank with a filter used for tanks up to eighty gallons. These fish need vegetables in their diet as well as frozen brine shrimp and blood worms, and of course - flakes/pellets.
Do NOT get a common Goldfish (AKA Koi, Comet, etc) if you do not have a pond or a 60 gallon tank at least per fish, since they grow to be very large and need lots of swimming space.
Fancy Goldfish are playful and social. They need to at LEAST be put in pairs. One of these fish needs 20 gallons at least of filtered water to live. They grow about 6" and live to be around 8-15 years old, depending on the amount of care they have.
On the other hand, if you don't want to buy a 40 gallon tank, you can buy a couple of Guppies. These fish do require a heater since they are tropical, but you can't put "cheap" and "fish" in the same sentence together since if you want your fish to live a long, healthy life, they need lots of care.
So invest in a 15-20 gallon tank. If you get a 15 gallon tank, you can put three guppies in it, and four guppies if you get a 20 gallon tank. Buy either all males, or all females, because these fish breed like crazy. They live to be about 3-5 years old, again depending on the tank and care given. They can be fed the same thing as Goldfish.
Good luck!
PS: Remember to cycle your tank first.