Does anyone ever had issues with US Customs buying parts from online shops or other forum members selling their parts overseas?

I was wondering if Customs charges you fees to pick up your stuff or to clear it from them. I'm curious coz I'm thinking of buying something from a shop overseas and it says that in the site that international customers are responsible for customs charges.

Or did any ever ordered a part from overseas without any hassle at all and received their parts without additional cost?