Kenny Hill makes these. He has an awesome guitar series that he makes as well. His workshop is out in Santa Cruz mountains of central california. His ukes are fantastic! (So are the guitars). I know that in the past he had made guitars in Mexico and did finish work in California but I heard he stopped doing that. I think his ukes always came out of California although I had also heard that he got involved with a prisoner work program and perhaps the ukes may be coming out of that. Anything he does is top rate!! I had a chance to get a concert about 7 years ago but I didn't bite the bullet and I've regretted not getting it. It was a island style construction and had the rope binding and came with a simple bag.
His website says both (soprano and concert) models not available. Checking his address in Felton, California he is my sister's neighbor. I think I'll go bother him next time I visit her.
I always find it unusual when luthiers at the their peak suddenly stop production (Kawika, G-String, etc.).