This style worked well for me. :) I raised Painted Ladies (Vanessa cardui) VERY successfully in them and Monarchs (Danaus plexippus) have plenty of room to flutter about as well. I sewed velcro to seal the 'door' on one of the houses but on another I just used wooden clothespins.

It may be more expensive but you may just want to go with what I have. More light would probabaly be able to filter in also for them, but I dont know.
The link below is what I got (the larger one)...

Here is a link that might be useful: Butterfly cage

Thanks tdogmom; naturally the TRU I checked had none, but I'm going to check another. Saturnii: those look very interesting. I might consider one to use inside for my monarchs, if they ever show up...