I have had very similar experiences with Congress for clients in several counties in Texas and New Mexico. When I insisted on a Purchase and Sale Agreement, they generally back away. If you have evaluated your needs and know what you want in a transaction, ignore the big hollow offers and follow Tom Ed Moore's advice. There are plenty of legitimate buyers looking for minerals in and around Howard County that will be happy to make fair deals using PSA's and use deeds that don't leave the seller with title liabilities forever.
Gary L Hutchinson