@Sean Dezoysahere are my thoughts on this strategy:
30 days might be too soon, most wholesale contracts have provisions to extend for another 30 days, and I regularly see several extensions pushing the contracts to 60-90 days. If they were distressed 90 days ago, chances are they are even more motivated now.
You can't get this "failed wholesale contracts" list from a list provider, so you would need to have a VA scrub manually through your emails or Off-market marketplaces to track those leads, which can be a daunting task but is doable.
I will pull the title to ensure the previous wholesaler didn't record a memorandum of interest on the property, as we see more and more of that. We have ways to get rid of those but it's time-consuming.
Lastly, the previous guy probably left scars and your negotiation is not gonna be easy, I would come prepared with a credibility package, POF, and be ready to dump a large EMD.
I hope that's helpful ;)