As a suggestion you can usually pick up small tanks really cheap locally... Ecen walmart. with shipping you take risk of it breaking, and you will probably pay more overall... just a suggestion
I agree with sporty.... how small do you want? You can get small tanks cheap at the store: 10 gallon tank only- $8 at Petsmart (u.s. dollars)
10 gallon complete kit- $25-$50 (u.s. dollars)