I'm not sure what your price range is like, but both of theses cage are pretty cheap but still an acceptable size for canaries :) a single bird will do great in it - plenty of room to fly back and forth.
24"x11"x18" doesn't even hit the minimum size for 1 budgie, unless they get to spend a lot of time outside the cage. Unless you upgrade, two budgies will feel cramped in there.
Budgies are best kept in even numbers 2,4,6 If you get an odd number, the 3rd budgie will get left out on socializing when the other two pair up and you'll have to deal with jealousy aggression and fighting, especially in a small cage.
This is the minimum you need for one budgie or two bonded budgies: https://www.amazon.com/You-Me-Finch-Rectangle-Flight/dp/B074P4T56Z and they'll still need time outside the cage to exercise properly. Edit: Forgot to mention dimensions, it's 30"x18"x18"
For 2-4 budgies, you'll need a much bigger cage like: https://www.petco.com/shop/en/petcostore/product/prevue-hendryx-large-black-flight-bird-cage