To be fair, the charge includes both shipping the kits to you and for you to ship the kits back to them, so the price isn't as bad as it looks. But I do agree with you that it can be lower.
And customs duties. They are not trying to gouge you, AFAIK.
There won't be duties as it's under $1000. I did realise after that it included the return postage.
@Dramatize: but the US might charge them import duties when you send it back. Not sure if the US has a duty-free allowance like we do.
To be fair, that is for return shipping on two kits (you have to send the kit back to them for testing).
That said, hopefully they do some A/B testing on shipping prices next ;)