Free: Contests & Raffles.
If you're pretty sure they've never been called before I'd start with the basics. Rabbit distress. If you're talking about a localized place where they're really aclimated, then I'd start by planning how you're gonna call next time in a different spot with a different approach and a different sound. Plan out several approaches that they won't see as related. Then you can hit 'em 2 or 3 times over a week or so and won't have to let the place cool down too much.
I talked to my aunt today more about the problem, and I guess the yotes will come stand basically on the back patio out by the hot tub. The yotes have also eaten all but 2 cats (one of the ladies had 6 to start with), and one of the two cats will no longer go outside. The yotes have also attacked one of their dogs, so it sounds like they are hungry and should come flying in to the sound of a dying rabbit. I can't wait to go in the morning.
If they are eating house cats, try a "feline in distress call".
Is there somewhere I can download a feline in distress sound? Try Feline distress calls here http://www.mscustomcalls.com/MP3.html