Milam County Mineral Rights - Price per acre?

What is the going rate per acre for Mineral Rights in Milam County, looking to buy 112 acre and want to know what to offer for mineral rights?

I’ve heard of leases over the last year in the $400-600/ac. range so I’d think you’d have to be in that ballpark or more. Etoco drilled a Buda well, the Spifire unit that was very successful so interest may be increasing. Valuing minerals is tough because of the unknowns and optionality associated with them.