I don't know how the transaction went, but you were always free to pass. I've walked away from a lot of sales counters over the years and never regretted it.

Some hardware is available at hardware stores, other stuff is better bought on-line. I do agree that the shop was entitled to top dollar for a hard to find derailleur part, but still $10.00 was high.

The irony is that overcharging for small stuff won't pay the rent anyway, and the cost in customer alienation is greater than what they made. I know I'd think long and hard before being a jerk for a lousy $30.00.