I actually registered on this forum (after lurking for a week or so) to follow up on this. I would STRONGLY recommend against ordering from dsflashcart.com
I ordered a R4i Gold 3DS from them on August 17. I received a confirmation email immediately, along with a UPS tracking number. The tracking showed a label was created, but UPS never received the package. This tracking information has not updated since then. I emailed eight days later, just to be sure everything was ok, but didn't get a reply. I emailed again five days after that, and got the following reply:
Hi, thanks for your email. So do you mean that you still haven't received your package? It's so weird, it has been two weeks now. Would you pls check your mailbox and also ask your friends, family members whether
they received it for you and if still can not find, can you call the local USPS if they can offer more info, we will also check more for you, thank
It was immediately obvious that they didn't even look at my invoice, let alone check the status of my order. I checked my mailbox (again), asked my wife, checked my home, asked my neighbor, and even went to my post office (they couldn't help, considering all I had was a UPS tracking number) to make sure I hadn't missed it. Having conformed I hadn't missed it, I emailed back letting them know it wasn't here. They did not reply. This brings us to August 31. Since then, I have emailed five additional times (no more than once per day) simply asking for an update. I still have not heard back. I emailed their payment processor (befound-online.com) explaining the situation, but didn't receive a reply from them, either.
At this point, I have pretty much given up hope they will send my order. I can deal with losing the money, but I can't get those three weeks back. I ended up ordering from nds-card.com instead (who have been extremely communicative), which I found thanks to GBA Temp. So yeah, in short, if you're reading this and plan to order a flashcart, I highly recommend NOT ordering from dsflashcart.com
EDIT 9/21/16 - I'm past the one month mark, and I have still received neither my cart nor a response from this vendor. It's safe to conclude I got ripped off by them. I strongly recommend avoiding this website.