Might not be yellow, but Vice offers a lime green color on their balls and they run $25 a dozen for their premium balls and down (though you do need to buy bulk). I'm currently playing lime green Vice Pro Plus balls and don't see myself changing anytime soon.
Cut Golf offers a 3 piece matte yellow ball for $20 a dozen. I don't have any experience with their matte balls, but I like their premium balls.
Both brands require you to order online.
Vice Pro Soft