After I had filled out my 'guide assisted' applications for Nevada I was directed to Nevada's fund raising raffle.
http://nvdreamtag.org/
They call it their Dream Hunt contest and you can buy as many tickets as you want on California or Desert Bighorns, deer, elk and antelope. I can attest to the size of the deer in Nevada as I have frequently jumped shooter 4 points when I have been lion hunting around Ely. Nevada manages for quality.
Anyway, $20 plus or minus gets you a crack at a Desert Bighorn so if you need one for your Slam or like me are working on #2 this would be a great place to start.
David