Out of the blue Looking for Lease on our Mineral Rights

100% owner of mineral rights on 50 acres, C.B. Kirk #1, #2, #3, #8 and #9 in San Patricio County.

Last week contacted by someone who wants to work up gas production lease for $300/yr per acre ($15k yr) and 1/5 royalty.

Would be curious as to this is in the ballpark, and what production would be estimated in this area?