Correct me if I am wrong, but reading through the given websites it looks like a Residencia Permanente costs 12,000 for a renewal of 4 years which comes out to 3,000 a year.
A Residencia Definitiva costs 20,000 and is good for 5 years which comes out to 4,000 a year. So, what is the advantage of getting a Residencia Definitiva?