My parents own a 3 story building in Bushwick Brooklyn. Some guy is trying to buy the air rights to their building and has offered $50K, $100K, and now $250K. My parents are now very interested in possibly selling their air rights, but are concerned about price because they don't want to get low balled knowing that this guy's offer went from $50K to $250K, they think the air rights might even be worth double. In order for them to feel confident in negotiating they wanted to consult a professional who can give conduct a detailed analysis for the air rights market value on their building, future projections, opportunity cost, etc. Could someone please point me in the right direction? Is there a specific type of Real Estate professional I should be contacting? How much do you think it's worth for this type of analysis report? Could I possibly get this info for free online? Any other recommendations or advice about selling or not selling air rights? I know very little about real estate so I appreciate your patience and professional advice. Thanks!