In Germany, there is no tax whatsoever for an item value under 22 EUR. There is 19% import turnover tax for item value between 22 EUR and 150 EUR and there may be additional import taxes for values above that depending on the type of wares. There usually isn't any addidtional charge for items related to computers/computer parts, at least I've never paid more than the 19% import turnover. Customs officials usually have no idea what computer keycaps cost or assume them to be low in value.
But the most annoying thing about customs is the additional delay in recieving shipments. Sometimes the damn customs processing takes weeks.