Aldi is rather like the Walmart of Germany - which is why Walmart was run out of the country. Certainly not as big as a Walmart store, but they have pretty interesting specials.
They buy low cost items with minimal overhead and sell them inexpensively. Such as this bike which is Chinese, not German. more and more, Europe is getting flooded with inexpensive Chinese goods just like the US. You can even buy inexpensive Chinese cars in Europe.