Where to buy R4i Gold 3DS Deluxe/Gateway/MT-Card in USA ?

BRECKENRIDGE, Colo. - Feb. 19, 2014 - PRLog -- Last week, I got myself a new zelda bundled 3ds xl, and without much research, I upgraded my firmware to 7.1.0-14U. I thought I could got a 3ds flashcard to play the 3DS backups(like Pokemon). But it later came to my knowledge that none can work, because all the current working 3ds flashcarts only work with lower system version 3ds console, and your 3DS has to be on software ver. 4.1 to ver. 4.5. And I traded my 3DS for a system version 4.5 console. So far from what I've gathered,you can not downgrade your system version, also I have no idea when the latest 3ds version console will be hacked. Now, there are three options for me: R4i Gold 3DS Deluxe Edition, Gateway 3DS and MT-card.
1. R4i Gold 3DS Deluxe Edition
Around $60-$79, compatible with system firmware v4.1 to v4.5, you'll be able to play 3ds backups as well as ds backups, but one game per microSD card at this time, the multi-game support feature will be released in the upcoming new v4.0 firmware. The team behind r4i gold 3ds deluxe is amazing, they update the firmware incredibly quick, and it seems to receive the most support compare to the other flashcarts. And it is probably the best flash card you can get, and i got mine this authorized official seller http://www.r4flashcart.com/20-r4i-gold-3ds-deluxe-edition... US based, so shipping was super fast.
2. Gateway 3DS Flashcart
Around $89-$95, compatible with system firmware v4.1-v4.5, more expensive compare to the other 3ds flashcarts, but they are the first team to release the world's first working 3ds flashcarts.
3. MT-card
Around $69-$75, requires system version v4.1-v4.5, it is the only flashcart that allows you to play multi-rom games with one microsd card, and you can change the games via the physical button directly.