The second gaming PC I built and sold in the course of a new business venture was destroyed by the USPS on its way to my customer back in 2008. Looked like it had been dropped from a helicopter.Yep and you can forget getting any kind of customer service. That'll never happen with usps.
Thankfully, I had it insured for the full value (just over $2k). My customer was very restrained, in my opinion. Not me so much. Even though a damaged/destroyed parcel is usually considered a matter for the recipient, I told him I was on the case, and then spent the next week-and-a-half leaning on the USPS.
They came through in the end and sent a check for the full amount of the system to my customer, but I honestly believe that if I wasn't on them about it every day, they'd have taken their sweet time. He might not have gotten paid for months.
And yes, their customer service is poor-to-nonexistent. I had to step in and "become" their customer service dept. for my customer. And needless to say, I never again shipped one of my systems via USPS.