Is it more expensive to use a mailbox etc. type place [Mail Service Company] than a post office for postage?

I just started a new job where a main post office is not close by. I found a Mail Service place right across my job which accepts FedEx packages, UPS, etc - like Mailbox Etc.



I need to ship to Canada, and I'm wondering if I use them, will it be more expensive since it isn't a post office? Do they add charges on top of regular postage?Is it more expensive to use a mailbox etc. type place [Mail Service Company] than a post office for postage?
sure it is. They have to make a profit in order to make a living and pay their bills