where to get self-locking footlocker?

I'm looking for a trunk or footlocker to put outside my house for the UPS/FEDEX/USPS to drop packages in. I want something with a built-in lock so they only have to drop the package in and close it. anyone know where I could get one? there are some on walmart's site and amazon, but it looks like they need a padlock (I don't want the UPS guy fiddling with closing a padlock).

I don't need much, just something I can chain up to deter someone from walking off with the package. heck, I would consider strong plastic. my neighborhood isn't bad, but you never know.

I don't need it to be big, 30in wide should be all that is necessary. I mostly get a bunch of small packages.