Yeah, it's really a shame the way most rewards on the Club Nintendo site are distributed. The most popular rewards that are offered often sell[size=78%] [/size]out incredibly quickly. The only thing that prevents that seems to be if the coin cost is extremely high, and even then it's not a guarantee (such as the Kirby Medal, which I believe was 1000 coins).
I also wanted to snag one of those snazzy Red 3DS XL reversible pouches, but they were sold out for the longest time, and when they were re-added, they immediately sold out again. Now they've been replaced with two colours that I am not at all interested in.
It's as though they intentionally limit the number of their cooler rewards. Sigh.