You won't be charged tax..
Question, what car are these gonna go on?? I see you want 8" rims for the front, and if they're gonna go on a GS you should go with 8.5"..
19X8 & 19X10 would be $3,170.
18x8 & 18x10 would be $2,755.
These prices do not include shipping.. And there's no need to bother trying comparing these prices because they are the lowest you'll find.. Shipping from Japan to your door will be about $300.