I plan to buy some electronic equipments from a supplier in china,worth about 400 USD, is there some kind of "TAX" I have to pay

I plan to buy some electronic equipments from a supplier in china,worth about 400 USD, is there some kind of "TAX" I have to pay
There would be no federal tax. However in theory you would be liable for your state's sales use tax. Rate is the same as regular sales tax.

You may have to pay duty when it arrives also, but most electronics is duty exempt, depends where you live though

Not my area of expertise.