A decoy is the least needed piece of equipment for being successful at killing predators. You'll be better off spending that money on a few different calls. I'd suggest an enclosed reed call or twoto start with. The enclosed reed call is very easy to use, and is effective. Maybe buy an open reed or two also. They are more versatile at making different sounds, including coyote vocals, BUT to get started, the enlcosed will be hard to beat!
At this point in the season, the coyote pups have dispersed and are easy to call in with simple distress calls. Stick with that for now, it will work just fine!