R4 will most likely be out of stock because Nintendo is working with law enforcement in many countries to crack down the distributors... If you are in Japan, no one will dare to advertise "R4" because of the legal issues. People will just walk around telling other people R4 is in stock.
Other than R4, there are other compatibles products out there in my opinions are better than R4. The M3, G6, EZ-Flash are all great products.
cheapest is go to zellers, buy a ubisoft game for Wii at $14 (some onsale now, just bring to the counter and scan it), then trade the game to EB games, with this trade, you can get a NDS for $99.
btw, that $14 dollar game also qualifies for by 1 get 1 free as well. enjoy.
New LYK is not user friendly and is annoying. Now you can blow me.