Many chinchilla owners are happy with a modified Ferret Nation cage. The modification is a metal pan that's made for chinchillas that you'll have to order that's made for the FN cage since the stock cage's plastic pan
can be chewed through allowing your pet to escape (and plastic can cause bowel obstructions) and also not deep enough so it's messy.
I use a heavily modified parrot cage. It is all one level but it's about 5' tall. The floor had to be replaced because the original floor was not safe. You can see more about my project here. Note that I totally went overboard on this build and it is not a typical cage.
http://www.chinchillaclub.com/forum/index.php/topic,4091.0.htmlMartin's cages makes a decent cage as well although it may come with wire shelves and ramps. Do not use wire shelving or ramps with chinchillas because they get their feet broken on them. I hear about that all the time and it can be fatal. Always use solid shelves. Ramps are unnecessary since chins like to jump.
Guidelines:
The bar spacing on the floor must be a maximum if 1/2" x 1/2" grid.
The bar spacing on the walls should be a maximum of 1" x 1/2".
For newborns and pregnant chinchillas there are additional requirements.
It is very important that the floor and wall joints of the cage be tight. They can get their toes caught in small spaces.
(Edited - apparently FN cages cannot be chewed through but I am familiar with cages that can, and have been. Thanks kageri for the correction)