I just flew with a playboat wrapped in felt and just plan called it a surfboard... $150.
Last year as an experiement I had my Huge Experiences staff and some students willing to try to attempt flying with creek boats. They came in right at 50% success rate. Flying with a creek boat is a bit tricky, has a risk and not for everyone.
Cargo can work but it's not worth the hassle and costs for one kayak.
Buying new via Kokayak or Rivers, Lakes and Oceans is outstanding that these guys can match US prices after shipping and import taxes.
Renting for $20/day is also impressive. And as the owner of Pucon Kayak Hostel
I'm happy to give extended country stay discounts.
So, you've got a lot of great options.