I know you got a response and everything worked out but I thought i might as well post my experience with nds-card, especially since it might help others still on the fence about ordering from them
Both of these orders were made with the "Hong Kong Registered Air Mail" shipping option, it was free for my second order, because order was 40+ dollars, but for my first order i had to pay 2 dollars.
I've made a couple of purchases recently, a R4 and a couple of Acekards. I, as most new people to the site, was a bit worried when i had to contact them for my order and then send money to a seemingly random email that they have provided. Everything went fine, my order took about 3 days to ship (I'm guessing it was because of the recent flood of orders that came with the release of ntrboot). I received a email with a tracking number telling me that it will arrive in 7-20 business days and that was all I heard from them. I refreshed the USPS website every few hours to see if anything change but it was stuck at "origin post preparing shipment" for a few days. It ended up in the US within 5 days, according to the tracking number. The package arrived in just 6 business days, one day earlier than what they told me would be the minimum.
I then decided to order the Acekards. It went a lot quicker since it was a few weeks after ntrboot released. When i sent the payment i decided to message nds-card and let them know that the payment has been made and that it will show up in one day, according to PayPal. They quickly messaged me back and said that they indeed did not receive the payment yet and asked me if i could send them a screenshot of the transaction on PayPal, and so I did. I got a couple emails shortly after, one said "confirmed thanks very much" and the other one was the usual email they send to anyone who has sent them a payment and that it has been received. They were nice enough to send me the package right away instead of waiting to receive the payment same tracking number situation where its stuck on "origin post is preparing shipment" message for a few days and it arrived at my home in 9 business days.
In my experience, I received the items I ordered and pretty quickly too, although that last part is more of a bonus, don't know if i just got lucky with my orders arriving quickly. Keep in mind that once they ship your package they have no control over how long it till take to get to you. For me, USPS handled both orders and they both arrived quickly. If i ever want a flashcart i will likely go with them again.
TLDR: Definitely not a scam, even if it might seem like it due to the weird PayPal payment method