Availability seems to be an across the board issue on parts these days, so where to buy is kind of a moving target. One possibly easy solution would be to simply have someone build on the hubs you have, unless you're wanting to keep a spare wheel set. I can't speak for your local market, but where I do business I'd charge somewhere between about $675 and $1k to build a carbon wheel set on your hubs depending on your choice of rim. Good "white label" carbon rims run around $200/ea. and lifetime warranty stuff like We Are One is gonna run about twice that, thus the wide price range.