You shouldn’t always assume the buyer is getting a better deal than the seller. There are risks associated with mineral rights ownership and acquisition the buyer is taking as well. This may include defected title (no ownership), potential the asset never gets developed/dormant minerals, costs incurred for tile, curative(clearing title from original owner to present day), etc.
You need to do what makes sense for your situation. When determining value, you typically need to consider the following: Leased/Unleased, % of parcel (do you have leverage in negotiations with operator to lease, Held by old vertical well (will never be leased again), Non-Participating Royalty Interest (can never be leased), exact location/positioning of parcel (could be cut out of a unit or stranded), volatility of gas/oil prices, if the asset starts producing revenue, management/accounting if it starts producing revenue, cost of out of state tax returns (if you do not live in PA), time value of lump sum vs. waiting.
Bottom line, the mineral buyer is looking to make an investment and of course would like to make a return. Very similar to a real estate investment, stock equity, etc., the buyer hopes/believes the asset will go up in value over time. They are typically spreading a wide net to offset the risks associated with specific parcels. Taking the variables of ownership into consideration, not all parcels are equal in value if in the same county. Ultimately, it is what someone is willing to pay today and whether you want to spend the time and money to figure out potential buyers, file necessary documents to clear title, hire landman to confirm ownership, negotiate a lease with operator (if applicable), etc.
I would love to get a random call saying that I own mineral rights somewhere. It likely took a lot of time and resources to determine that and potentially would have escheated to the state if that never happened.