Hey there, if you do an eBay search you will find loads of cages specifically for Cockatiels. Just be careful of spacing between the cage bars. 3/4 inch gap is really big enough, they like to stick their heads through and there is a danger of getting stuck. Our little Hercules hated her new cage and would only relax and rest in the cage we bought when we bought her, recommend to us.
As she has lots of time out we finally gave in and left her to her old cage, which is big enough anyway.
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