He knew his high bid did not meet the reserve amount, so there was no need to hold out hope of "winning" the auction.

I agree with the others. When the seller set a reserve price, he took the chance that the highest bid amount would not be the final say in whether the item would be sold. You are not obligated to make the purchase.

I guess I would teach the seller a lesson, though, and tell him that you appreciate his offer to sell, but you purchased a similar item when your high bid did not meet the reserve amount.