Organization of the relationship structure in the database: how to implement it?

Question

Database

Hello. I plan to organize a relation for goods. Each product may vary in price, depending on the quantity purchased.
For example:
The price of a vacuum cleaner is 6000 rubles, when buying from 1 to 6 pieces. When buying from 7 to 20, the price is 5000 rubles.
How to organize quantity ranges? What ideas do you have and how do you solve this problem?
Thank you for your attention.