Corners Limited - Custom made cages and aviaries. This companies stuff looks great, I plan on getting one of their aviaries one day. Send for their catalog if you are interested, it contains a lot more than is on the web site. Fox's Feather Farm - Very nice cages at very reasonable prices. King's Cages - Considered to be one of the best cages on the market.
Quality does come at a price though.
Avian Adventures - Manufacturer of premium quality cages and accessories. Animal Environments - Manufacturer of cages and toys. Macaws Only Cages - Manufacturer of very large cages for large birds. Palace Cages - Manufacturer of furnature quality cages. Watch out for cages with fancy grillwork as birds can get their legs caught in them.