Walgreen has their dog steps on sale for $10 right now 3/23/07. I have purchased the expensive all foam ones and I have purchased the plastic ones and frankly I would tell you to save your $$$ (unless you stub your toe all the time
)and buy the plastic ones. If you travel you take the plastic ones apart and put in your suitcase.
My gang ranges in size from 3#'s to 15#'s and everyone can get up on the bed using these stairs.