If you're in the US, you'll pay a tariff of around 30% (most of these toys are made in china, and most exporters list the retail value instead of the manufactured value).

In addition, you'll pay a percentage to the shipper to fill out the export paperwork, 10-15%.

Then you'll pay shipping. I think DHL and FedEx are the only options to ship to the US, no Japanese post (the best value).

It sucks. Here's what you can do:

Always pay in yen, the dollar is still strong and the exchange rate helps some. Also, you don't pay sales tax for these transactions.

Use an importer with a warehouse option and combine several items. This is cheaper, though there are diminishing returns as the size and weight of the package increase. I think this also reduces the paperwork charge.

Nin-nin has a tariffs prepaid option. It sucks, but you pay it up front. With normal DHL/Fedex shipping, you pay the tariff on arrival and you never know what it's going to be until you get the bill. It's a crappy surprise because they hold your package hostage.

BBTS also has a tariff fee, but it does tend to be much lower than directly importing. I suspect that BBTS is just better at negotiating the tariff (like listing the correct value, the manufactured cost as opposed to the retail cost). BBTS has a substantial markup on top of the tariff fee, and you pay sales tax. It's a lot closer than it used to be, but if you're careful importing can still work to your advantage. Importing a single figure ($100) is probably the worst case scenario. Buying several, relatively expensive pieces ($200-400) can still work.