[Always Right]

The book sales would be moneychanging at the temple.

It seems like Jesus was making the point about people ripping others off by overcharging for changing their currency into the proper type or charing high dollar for animals suitable for sacrafices. I am not sure how that applies to books Joel sells in bookstores.

[Bear_Slayer]

1) They were seated in the temple area and nejoyed a monoply.
2) They required adherents to use only certain coin, which only they could provide and for a fee.
3) Animals brought as offerings were inspected and often illeginmately found to be unsuitable, requiring one to buy a suitable one or exchanging it for coin -- at a cost.

Joel is seated in the temple area (so to speak) and enjoys a monopoly.
His books are usually kept in the church book store and members are encouraged from the pulpit and other's to buy the books. You can't suceed without them.

If joel really had the truth that helped christian's suceed at hliness or entering heaven, it would seem that by Christ's highest commandment, he would give the books away.

"Freely you have received, freely you should give."