If you're new to this 1/144 world, you may have a question whether you should buy from Japan or wait for the US version. From my experience, I prefer to wait and buy here in the United States.
The price of one Cando tank in Japan is yen380, which is around US$3.5. One big box has 15 tanks and you normally get 1-2 complete sets in one big box. One carton has 8 big boxes. It comes to 120 tanks in 1 carton. Normally you can get 4 special (in 4 big boxes) in one carton. It's kind of risky if you buy big boxes not one carton as there is no guarantee how many specials you can get. The total cost of 1 carton then is 45,600 yen. After adding the shipping or wholesale discount (not much for these trading kits), you may still need to pay 60000 yen plus for one carton which is around usd 550+.
If I buy from the US, the price is US3.95 each with 12 tanks in one big boxes. 4 big boxes is one carton. So you only need to pay around $200 (the shipping and wholesale discount normally offset each otehr) for 48 tanks from one carton. You normally get 2 specials in one carton. So, in average, you get 1 in 24 tanks and that's where the 4% comes from. In other words, in order to get 4 specials like you purchase from Japan, you only need to buy 96 and not 120. So, you get a better deal.
As I mentioned above, you normally pay more than 60000Yen for 120 tanks from Japan. I think each tank will cost $5+ if you buy from Japan. And you normally need to pay only $4 for each tank in the US. In addition, you get a display box as a bonus if you buy from the U.S. So, you should know where to buy from, right?
Last but not least, the US version is sealed in the blister rather than a blind box. You don't need to open the box in order to know what's inside. For me, I keep all the specials sealed in the blister as I think it will have a better value. You can't do the same for Japan imports.
I'm getting old so I'm more patient. I normally just wait for the US releases. However, if you don't want to buy the whole carton, the above analysis does not apply to you as I think the price is pretty much similar for the same tank no matter it's from the Japan or US. The only thing impacts the price is just supply and demand. Please feel free to let me know if you find any errors in my analysis above. Talk to you again tomorrow.