I would be wary of any “as much as” offers. I get those types of offers all the time. The high end may be related to a 25% royalty or may be totally bogus and just used as a teaser to get you to reply. Many companies send out mass mailings like that.
My assumption is that any time I get an unsolicited offer, the offering company knows something I do not know and they certainly plan on making a profit off of me. I ignore them and try to find out what they know. Usually, they know about drilling about to occur.