I'd be a little leery of open cows with weaning aged calves unless you know why they're open and it has nothing to do with fertility or unless your plan is find them before breeding season and speak for em on the terms they're left open for fall breeding. There might be people, though, who'll have some late calving or summer pairs with cows left open for fall. Probably depends on where you're located...some areas typically calve more cows in the fall than other areas. But there again, late calvers in a spring breeding program could be the cows that don't keep up on calving intervals, and if I'm spending the money and going to the trouble, I want the most fertile and most productive recip prospects I can get my hands on.
Just kinda thinking out loud... Good luck finding something!