"For the sake of argument, let's say I'm an avid reader who buys two paperbacks per month from Amazon."
Too much conflation to be sure of buying and reading and where one buys from, but it is not unreasonable to assume he means his reading for the month are those two paperbacks (not that a seriously avid reader works this way, but bear with me here).
That's not avid.
ETA: He says shortly thereafter:
"That brings my two-paperback-a-month habit (books + shipping) to $447.12 per year." further supporting the hypothesis that this is the extent of his addiction.