it's not just leftists that launder money through "book sales"
thrift books is a large online seller of used and excess books on ebay
if you search o'reilly you will find lots of his books listed as "more than 10 available"
"160 sold" etc
they sell for around $4.20 to $5 with free shipping
they list them as "pre-owned" but most of the later released ones look new