I need to courier something worth about NZ$4K from Wellington to Christchurch for repair - it's not large or heavy. NZPost / Aramex both limit their insurance to $2K for retail customers, though they do have higher limits for commercial customers. Does anyone know a courier company that will make it easy to courier this with appropriate insurance?

I'm also going to ask the repair firm if they could arrange collection using their courier, but I suspect the answer will be "no that's too much hassle for us".