Crates/Carriers/Ex-pens : JB Wholesale Pet Supplies
I've found that this site has very good prices on crates. I would caution against the "drop pin" crates. They are a real pain to deal with, and are only slightly cheaper than the folding crates. I have one and I would never ever get one again.
In order to give a "cave" feeling to a wire crate, you can drape a sheet or towel over it to cover it and give a bit more privacy at times. Not a bad idea with puppies, because even though they like to look out they also can get too distracted and forget to curl up and sleep.
It also depends on what breed of corgi you have. For a Cardigan I reccommend a Minimum of 30" in length for comfort, while Pembrokes may be able to make do with a bit less since they are somewhat shorter in length.
AJ