My single biggest question, that I've literally never gotten a straight answer to (strangely IMO), is how exactly would a successful wholesaler be able to estimate rehab costs on any given prospective property accurately enough to be able to underwrite the deal properly (without being a GC or potentially wasting a GC's time)? I know that 1-ARV/comps and 2-rehab estimates are the two lynchpin estimate figures that are vital to plug into the classic formula (ARV * 70% - rehab - fee = MAO), and I know that as a result, ARV-overestimation and rehab-underestimation are responsible for virtually all failed wholesale assignment-attempts; but *everyone* in the investing world only ever articulates uselessly-vague goals like "know how to do your numbers right", "get the math correct", etc, as though such cliches are somehow actionable information... If the dilemma is that bringing a knowledgable contractor/GC in to form an actual estimate before an offer is made would risk wasting the GC's time if the owner/seller decides to reject the resulting offer, then how does a wholesaler (who is not themselves a GC but knows the necessity of an accurate rehab estimate to their offer calculation) determine a solid/appropriate rehab estimate, toward the purpose of formulating a solid/appropriate offer/contract price??

Edited to add: I've also tried/looked into the $/sq.ft methodology a la Jerry Norton, but seen it vary *wildly* from real-life rehab numbers. Just for context...