There's a little more to it than that! Kailua sand is very white, but more importantly, very fine. I asked about using Kaneohe sand -- not much in the way of beaches here, but there's a beach at the bottom of my hill only at low tide -- and the answer was that they'd probably have to grind it first, since, unlike in Kailua, there's no waves around here. (They break well offshore around Kaneohe.)
(Before I understood the nature of the sand, my assumption was that they picked Kailua because that's where both Joe and Kristen Souza were born. That's true, but like I said, there's a little more to it.)
The complicated part is that it's illegal to remove sand from Hawaiian beaches, and indeed virtually every beach on the planet, without a permit. (Fascinating story about this, and the black market arising from it,
here.) Fines for collecting sand without a permit in Hawaii go to to $100,000! And seriously, the article I linked to explains a lot of why.
(Most interesting to me in that article is that India's richest and most powerful crime cartel isn't trafficking drugs, but
sand! And if you're wondering how global warming is accelerating the loss of sand and therefore driving up the cost of everything from highways and highrises to iPhones and eyeglasses, by all means read on!)
Kanile'a most definitely has a permit for collecting sand, but it's for a very small amount, hence typically reserved for fret dots, some (not all) logos, and occasional embellishments like this Islands series. There's just not very much available.
This set of ukes is in the Build to Order collection, which means a couple of things. One is that you won't typically find it at retail. You place the order, and they build it.
The second thing is that while it isn't super explicit on the page, you can in fact do some customizing on Build to Order models. The specifics of what can be customized and how vary by model, and needless to say, will almost certainly affect the price, but the whole point of the process is to get exactly what you want, so get in touch with Kanile'a and talk to them about what's possible.
I'm still learning about this stuff, but I hope that helps a little!