There's customs and import fees. Then sales tax is added as a percentage of the sales value PLUS all the fees. At least in Sweden. And here the sales tax is 25%.
So, yeah, there are fees but only if customs decide to check that particular box. The one you sent me escaped that scrutiny.
But you shouldn't agree to any deals. He's only buying from the states because it's WAY cheaper than in the Netherlands. Sure, taxes and shipping worsens the deal and many times it isn't economical to buy directly from summit unless you can do what I do, pack multiple orders in one box and ship USPS. But buying used parts that are hard to find vs buying new locally is way cheaper.
Of course it depends on what it is you're selling.