I,d look for a used bolt action in what ever caliber is allowed for coyote hunting in your state unless you're gonna take it out west for praire dogs you should also get it in a caliber suitable for deer. Since you mentioned the sks .30 cal sounds like an option. So anything from .223 to .30 in a good used gun like any basic model Savage Remington etc.,. Or a Swedish Mauser should sell for under $300 and makes a great coyote/deer rifle with the right loads. I'd stay away from the sks though not bad but not the best sights or easy to mount a scope solidly.