I need to get hold of the type of small bird cage that you see in a pet shop. base, back, sides and top in wood and a wire front. The reason for this is (a) if I had to take my cockatiel to the vets I could never take him in his huge cage, so a small portable cage would be good and (b) I am thinking of getting another cockatiel and would need to keep them apart in two cages for a few weeks. I don't have room to buy another large cage and would not use it for anymore than two weeks, so if I had a smaller "pet shop" cage this would do for all uses. Can I get one anywhere?
Why not try ask ing the pet shop owner if they can order one for you - if they're nice like my local one they may even let you have one of their old ones.
They are often used as (and referred to as) breeding cages - try looking in your local free ads paper or even put a wanted ad in for one.
Other than that can't you find maybe a retired gent who makes bird tables to knock one up for you?
I would seriously reconsider what you are doing. Keeping any creature in a cage is very cruel. These are intelligent birds and get very stressed when kept in captivity.