This is such a scam. They also make it as hard as possible for you do do your own custom clearance with border security. Though every time I do get a UPS shipment I'll tell them I'll self-clear it. It costs significantly less, but I having to drive 30 min to get it cleared is fairly painful depending on how much cost I'm trying to avoid.
So yeah, I suggest learning how to self-clear, even if it's just so UPS doesn't get that little bit more in scummy profits.