Complex sentence: However, unofficially, goods were sold at reduced prices by many stores throughout the whole of January and by the time that the sales officially begin the only goods left on sale are low-quality ones, often specially manufactured for the sales.
Split into simpler sentences: However, unofficially, goods are sold at reduced prices by many stores throughout the whole of January. By the time the sales officially begin the only goods left on sale are low-quality ones, often specially manufactured for the sales.