Your search asking for koa ukulele has given the following available right now for sale on eBay.

Things you might try to refine your search:

- add the size of the ukelele e.g. soprano, concert, tenor or baritone.
- include brand of uke e.g. Martin, Kala, Lanikai, Oscar Schmidt.
- stipulate the wood the uke is constructed of e.g. koa, mahogany, acacia, spruce.