I've always thought first-sale doctrine is an interesting and important check on price discrimination. People usually get angry with the concept of price discrimination, it seems to grate at the idea of fairness. Poorly or improperly implemented price discrimination coupled with a strong first-sale doctrine will lead to interesting new arbitrage opportunities.

The pending case of Kirtsaeng v. John Wiley & Sons, Inc is a good example of arbitrageur vs price discriminator. The result of witch will be really important.