If the issue involves potential litigation I don't think "a tiny cut of the deal" will have any competent takers. A garden-variety demand letter from a known oil and gas litigator will run you $1000-$1500. After that, hold on for the ride cause you are headed for some big bucks.
The lawyers I know who worked with landowners in the boom days usually got a fee per acre or a small percentage, but these were very large tracts, most in the 300-2000 acre range. The cut a fat hog. Phillip Downer is who I would strongly recommend, he is a no nonsense type of guy, not your typical land shark lol. I would use him especially in any situation that was going to require litigation.