Wholesaling 101 Question regarding offer price

[GaNeane Lewis]

We are brand new to wholesaling and have been spending the past month immersing ourselves in webinars, podcasts, training, etc. We have all of the formulas down for building a deal, determining ARV, rehab budgets, etc. We've even invested in deal analysis software. The ONE THING that is eluding us is that EVERY formula (be it software or not) starts with one thing: the price that you will acquire the property (which is obviously NOT what it is listed for). I've been searching all over but I cannot find a formula that will help determine THIS particular number (that everything else is dependent upon). What I have been doing in my mock deals is looking at comps and using an average number based upon square footage in the comps. But I don't know if this correct or not! Does anyone have a formula for determining what your purchase price should ideally be compared to list price? Or am I missing something obvious?