I would sugest the Ubbi Steel Odor Locking bin, it uses normal bin liners so safes you money, I have not used this one myself but have heard good stories.
As a Parent (and DL) I have noticed that the plastic bins start to smell after a while. We have a Tommee Tippee Diaper bin, it's become a little smelly over time but as we still have those propriatary bags we will keep using it till finished.
I slip mine in too on ocasion. ?