Reptile Depot can be a little slow sometimes, but they add something that I have not seen offered by others. They add an extra door on the front of the cage. This door really helps with cleaning. Some places offer to build custom sized cages as well.
you may also go to your local pet store... i dont think a petco would do this, but a pet supermarket or another pet store. you can ask the manager to order you the cage with the dimensions. the link brad gave your www.cages.net is avery good site i had the pleasure of meeting the owner. i have 2 of his products and i highly recomenned them.
there is thread here on making your own cage. its very easy and looks 10 times better. It costs about 100 and you get the best built cage " by you " and you save and it has a drainage system witch non of those offer.