As-Salamu `alaykum... I have a question about selling products...Is there a rule which indicates how much profit you can make on your products from an Islamic view...?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

The limit of the amount of profit that one may make out of selling products is not determined in the Islamic legislation according to the view of the majority of scholars. Nonetheless, a Muslim tradesman should not be greedy and egoistic and only interested in material things (i.e. money) in his business. Rather, the moral conduct should be his major concern and objective, and he should consider the circumstances of the public when buying from them or selling to them, and in all his dealings. He should always remember the saying of the Prophet : "May Allaah forgive a person who is lenient when selling, when buying and when asking for his right." [Al-Bukhari]. 

Allaah Knows best.