but where do you find the tubes if you want to do this yourself?

These look like the things you use to pour concrete. They're also what they use to make the round parts of cat trees. I couldn't find a link on Lowes but you can get them there and Home Depot.

For visual reference (Although they usually aren't yellow)

http://www.packagepavement.com/quiktube_use.html

They're called Concrete Form Tubes, they come in all sorts of circumfrences from like 4inches or so to 10inches (we cut little holes in them and our bunnies love to lounge and scurry through them). They're also relatively cheap, I think the 8inch one (they're all about 4 feet long at home depot) is only like $6. You can get them to cut them for you too, and end up with all the parts to make your own this type of shelf for about $10. They're also sturdier than regular hardboard in case you're worried about them not holding up.

meant cardboard, not hardboard sorry.

now that i know what cardboard tubes to purchase, any thoughts on how i attach these to the wall most efficiently?

I have seen this done with Silver Paint cans before, pretty cool stuff.

@ Rebecca_South and Julie h. : Any packaging store should have a 4ft tube for $5 or less. From there just cut it down to the desired length with a hand saw (metal cutting blade leaves a cleaner edge) or razor blade, then attach to the wall with clear heavy duty epoxy.

:D

P.s. don't forget to post your pics.