Libertarian literary translation question

A reader writes: I have found an excellent novel in Spanish by a long-dead author who is still just in copyright. He was already forgotten when he died, and has remained so. I’d like to translate and self-publish it. How much should I offer the rights-holders?

Boingboing: 17M = 17,000

Ms Jardin: The demonstrations were not limited to Madrid. Below: 17,000 en Sevilla … from Antonio Rull’s photostream. One wonders whether the writer may not have rather lost touch with her family name’s linguistic heritage, and she’s duly outed in comments by hewtwit: I live around the corner from there in seville (plaza de encarnacion)…