$20,000 for 8 months work isn't very much. It's not very clear how much time he spent per week but it sounds quite significant.
I could definitely use U$ 20.000, it's more than a year and a half of my (post-taxes) salary here in Uruguay.
(And yes, I should look into consulting, etc. HN is a great way to nag me to move forward and it's good advice).