Refusing to sell a negotiating budget as an engineered certainty

A landowner needed a road cost figure to underwrite a lot purchase negotiation. My team produced a contractor budget for the access road, and the landowner came back with fourteen detailed civil engineering questions the working budget was never built to answer. Instead of commissioning full engineering to answer every question, or pretending the working number already had that level of certainty, I reframed the conversation. What he had was a working negotiation budget, not a stamped construction set, and I named the real cost and tier of engineering it would take to get real certainty. Answering fourteen technical questions with hand waving would have been dishonest, and quietly funding full engineering before the lot deal even closed would have meant paying for someone else's diligence out of my own pocket. The honest move was naming exactly what kind of number he was holding and letting him choose which path he wanted to pay for. The negotiation forked cleanly into two paths, proceed on the negotiation budget basis, or he funds the engineering tier needed for construction grade certainty before closing. When someone asks a budget number to do a stamped drawing's job, don't dress the number up. Tell them exactly what kind of number they're holding and what it would cost to get the other kind. I respected him enough to tell him the truth about what he was and wasn't holding, instead of letting a rough number quietly harden into a false sense of certainty.