Do I have the right to put up a mailbox?

I don't have a mailbox at my rental property. It cost forty dollars to get a PO box. I just can't afford it. I would think that as a US citizen I would have the right to put up a mailbox at this property to receive mail without having to pay for the service. Everyone else in america gets there mail brought to them for free, why can't I? Anyways, the mail man would have to get out of his car to deliver if I did put up a box, put there are places all of the us where the mail man does this, so why would that be an issue? Even if there is no land to put one up on (I live on main st in my town) couldn't I still put one up one the side of my building next to my door, or even just put a mail slot in my door? If I do put up a mailbox on my own how do I get the post office to deliver to it and do they have the right to refuse to? Thanks, Amberlynn Gordon