Where to buy r4 flashcart for 3ds 7.1.0-16 in the US?

ARCADIA, Calif. - Feb. 28, 2014 - PRLog -- Today Nintendo official team updated the 3DS system version to 7.1.0-16. It was a minor system update which just adds further improvements to overall system stability, what's more other adjustments have also been made to enhance the user experience. And the version 7.1.0-16U isavailable to download now. According to many 3ds flashcart users, no flashcarts were blocked in this new firmware update, many r4i card users said their cards are still working great. And just updated my 3DS system to the latest 7.1.0-16U, now my question is which 3ds flashcart should I get? or which is the best r4/r4i flashcart for 3ds 7.1.0-16 J/E/U?
After reading around many websites,   r4i gold 3ds rts card was the most recommended. Because the development team behind this card release the firmware update extremely quick to bypass Nintendo 3ds update, with or without firmware update patch.http://www.r4flashcart.com/8-wood-r4i-gold-3ds-flashcart-for-3ds-xl-3ds-dsi-and-ds-lite.html its one of the few places still operating from within the US, so delivery is normally within 3 days.
I searched around and also found about 5 great cards for the latest 3ds console:

1. R4i Gold 3DS RTS card
2. Supercard dstwo
3. R4i-sdhc 3DS RTS card
4. R4i sdhc 3DS Dual Core card
5. Ace3DS Plus

Quote from Nintendo official website:
Update released: February 26th, 2014
Further improvements to overall system stability and other minor adjustments have been made to enhance the user experience.