So... ever had that moment where your fish tank cracks beyond repair and now you have this big space where you have so much space to make a betta area?
Yeah that.
Anyone know an online store that has cheap-enough five gallons?
Buying tanks online is expensive and risky. I do not know any online store with cheap five gallons.
You can try to see if anyone local has a five gallon they want to sell. If it was already used, it's likely to be extremely inexpensive and it is good to reuse!
Do you need anything besides the tank?
(at least in my area, has been there today) on Topfin 5.5 gal kit (tank, lid with small LED lights, HOB filter (I'd say quite a decent one, I moved it to the other 10 gallon), thermometer and probably some other small goodies for around $30.
I understand you need just tank, but I'd say if you plan any other small setup anytime soon (e.g. quarantine tank or something like this), it might we worth looking at this kit...
5 gallon tanks are harder to come by cheaper than 10 gallons. The 10 gallon are constantly on sale for $1/g at Petco. And 5g are rarely even in stock around me, aside from top fin kits.
And when 5g tanks are in stock and there is no sale, they're the same price as the 10 gallon.
I do all TopFin Tanks. SO much cheaper, i spent 78$ish on 1 LED 10gallon kit instead of $200 buying it all separate. Just buy a sponge filter and sell the filter given. Ive done this 6times already. I swear on my 20 gallon tank itself i bought it all separate and spent over $500 The tank was 120$ and the light was alot too...