When I was growing up in my home as a child, we were taught not to buy German products. This was the 1970's and the holocaust was not so far in the past.
Years have past and I often think about this issue. If we take it to the extreme then we can't buy Spanish products [the Inquisition]. Russian products [Communism, religious oppression], Polish products [terrible suffering] and maybe even American products [they didn't do what they could have to stop the Nazis and didn't let European Jews immigrate]. Not to mention all of the other countries that have caused Jews suffering [England kicked us out in the 1100's ימ"ש]. But due to my upbringing and my unwavering hatred of Germany and Germans, I try to avoid German made products if I can.
Here is letter from the Lubavitcher Rebbe on the topic [from the 15th of Kislev 5730]:
I am in receipt of your letter of November 14th, in which you ask my opinion “as to whether it is a weakness or impropriety” to avoid the purchase of goods made in Germany. You add that you ask this question as a Jew, in light of Jewish law and custom.
Surely this is more a matter of feeling rather than a question of Jewish law and custom. Consequently, as in all matters of sentiment, it is difficult to express an opinion that would have universal application.
At any rate, it certainly cannot be categorized as a “weakness.” On the contrary, a decision of this kind bespeaks strength of will, all the more so since it entails some inconvenience.
Nor can it be considered an “impropriety,” since it is based on a principle which may be considered to come under the category of “Remember what Amalek did unto you.” For, as is well known, the inhuman atrocities, etc., against our defenseless and innocent brethren were not perpetrated by a small group, but were carried out with the knowledge, consent and even cooperation of the vast majority of the German nation. Moreover, I do not think that anyone seriously believes that the Germany of today is entirely different from the Germany of two decades ago.