In a world where Miatas start at $23,500, that doesn't seem too steep. Also the Roadster in Japan costs $29,975 so the cars do get a little cheaper when they cross the Pacific. The forum post that I got the Roadster's price from predicted a starting value of $24,000 for the most basic FR-S.
That seems a fair premium over the Miata for the marginally-improved utility and extra power.