In Vayikra 13:52, the Torah tells us that one needs to burn clothing that was afflicted with tzoraas.  

The Tosefta in 5:13 says that if a Jew dyes the clothing afflicted with tzoraas or sells it to a non-Jew, the clothing becomes tahor. The reason for this is that if a non-Jew has an article of clothing with tzoraas on it, it would not be tamei; so too, if a Jew sells an article of clothing with tzoraas on it to a non-Jew, it automatically becomes tahor. The Rambam in 13:15 of Hilchos Tzoraas brings the above opinion down lehalacha

The Ohr Sameach and the Chazon Ish ask how can one sell something that is assur be’hanaah? We find that an ox that was sentenced to be stoned for goring a human may not be sold since it is assur be’hanaah. We also find the same concept that chametz after the time that it becomes assur may no longer be sold to a non-Jew. Why is it permissible for the article of clothing with tzoraas to be sold? 

The Ohr Sameach and the Chazon Ish explain that one may not sell an item that is assur behanaah in a case where it will remain assur behanaah in the hand of the buyer as well. Since the tzoraas clothing in the hand of the non-Jew would be muttar behanaah since clothing of a non-Jew is never tamei tzoraas, the sale would therefore be valid. In a case of an ox that was sentenced to be stoned, it would be assur even in the hands of the non-Jew; therefore, the sale is invalid. 

What about selling chametz to a non-Jew? The Ramabm in 1:3 Chametz and Matza, says that one does not get malkus (39 lashes) if he transgresses the lav of Bal Yeiroeh (chametz may not be seen nor found in a Jewish home.) The reason why one does not get malkus is because having chametz in one’s domain is not an action, but rather an act of passivity that he did not get rid of his chametz. The Rambam concludes that in a case where a Yid obtains chametz by buying it from a non-Jew, this will cause him to get malkus

The Noda Biyhuda in Vol 1, Orach Chaim 19, asks, how is it possible to buy chametz if it is assur behanaah? The Ran in Avoda Zora 18b, in the dafim of the Rif differentiates between chametz of a Jew which is assur Behanaah and chametz of a non-Jew. Since the Yid has a mitzvah to destroy his chametz, it is therefore assur behanaah and the chametz has no monetary value; however, by a non-Jew who has no mitzvah of destroying his chametz, his chametz will have monetary value. 

There may be no issur behanaah for the goy, but a Jew has an issur as soon as he gets the chametz and therefore the chametz would have no monetary value so how is he transgressing when it has no monetary value? The Ran explains that since chametz is a temporary issur - it is limited in time only during the Yom Tov of Pesach – it therefore has monetary value to buy and sell because it will become muttar right after Pesach. We see from the Ran that something that will become muttar after a period of time still has monetary value and can be bought or sold. In the case of an article of clothing; since it will be muttar as soon as it reaches the non-Jews hands, it therefore is considered as having monetary value even though it is assur behanaah

May we be zocheh  to do all the Mitzvos properly this Pesach!