OP has to sue Paypal in Santa Clara County, CA or Omaha, NE. California law will apply, which may actually be good for OP because California's consumer protection laws are pretty robust.
OP, I hope you sue the everloving sh!+ out of Paypal. At the very least, Paypal was negligent in ordering your property destroyed without having a neutral, trusted third-party authenticator declare it ("it" = the actual bag you sent the buyer, with your security tag attached) counterfeit. In my mind, Paypal is just as much at fault as the scheming scammer. It's downright APPALLING how Paypal operates.
I think others have already pointed this out, but there is nothing the seller could have done in this situation to protect herself from Paypal deciding in favor of the buyer. Even if the seller had filmed a UPS employee packing the box and obtained affidavits from the employee vouching for the packed bag being the same item as the bag that had previously been authenticated, we know--based on what Paypal representatives have told various sellers on tPF--that Paypal only "may consider" such evidence. Which virtually guarantees that Paypal would still decide in favor of the buyer even in the face of such evidence. It might help the seller prove her case in court--where evidence presented by both parties is actually considered--but as far as Paypal goes, it's just a waste of time and money.
this is good to know...