M.C.
You can by them online at diapers.com they are called huggies "slip on" little movers.
They look just like pull-ups to me. I have never tried them though. Anyways, they only come in diaper size size 3, 4 and 5. In disposable my daughter went straight into pull ups after size 4's. I bet they would be handy for early potty trainers though! we never used disposables much though, so I can't really say if there is anything else disposable like these...
I like cloth training pants or pull on diapers better, they have snaps on the sides and are absorbent, and would cost way less over time. Not practical for everyone... but I would rather spend the money on a reusable option myself...
good luck!
-M.