Where do larger companies buy their goods for profit?

Assuming a laptop is sold for 1250 euro in a media market, it must have been bought somewhere beforehand in order to be able to resell it later for more profit, but where? If it was an Apple laptop, would the company get volume discounts when buying direct from Apple? Where are these goods bought cheaper than in normal shops and is it accessible to people starting a business, if so when?

The shops get the goods cheaper than the normal consumer.

Yes, of course the big chains buy directly from the manufacturer.

Otherwise there are middlemen, including wholesalers.

This is always done individually. Apple is not a brand that is known for particularly inexpensive offers.

Manufacturers are asked mostly from Asia. It is negotiated at what price, etc.