Explanation:
The phrases "buy," "sell," "borrow", and "lend" are all related to barter. Most likely, the writer is attempting to emphasize the disparities between them, resulting in the paradox.
In order to create a paradox, in literary terminology, juxtaposition is the contraction between two or more notions. Like for example "Ask not what your country can do for you; ask what you can do for your country".
In conclusion, this kind of statement is known as paradoxical. An oxymoron is a condensed paradox made up of only a few words like buy and sell in this case.