Ok so sadly i have all the stuff for my Betta fish bowl and all but the thing is me or my mom dont have enough money for a heater >.< it wount be for a while until i can get one! D: and i dont want my fish to get sick, die, ect. soo is there anyway else to heat a fish bowl...? If so please tell me >.<
Do you have a room in the house that stays about 78-80F day and night? If so, you can keep it in that room. Or if you have a Space Heater, put the tank near it in a small room and keep the heater warming the room so the water is 76F or so.
My bedroom usually stays a steady 78 degrees, which is awesome for my fish, and my empty wallet! They've been healthy and active and are being their usual selves. You should be fine.
I'd suggest getting a heater once the weather cools down though... I was checking out the Tetra ones at walmart last night, and they were running $13-$19 each! Not all that expensive! I'll be grabbing 4... 4 heaters... wow. anyway i'll be getting several heaters in the next couple of months for my guys.
If your house is kept warm enough and your tank is 1-3 gallons the tetra heaters work fine IME. My apartment is kept too cold for the tetra to be effective but when I move it to a place that is kept 72+ degrees it works fine (which tells you how cold I keep my place LOL).
Topfin heaters from petsmart are relatively cheap (not as cheap as the tetras) and have a hi-lo adjustable setting. BUT I don't recommend using them on anything less than a 2 gallon tank. They only go down to 25 watts and IMO that would over heat a tank less than 2 gallons.