You say 'randomly' but you still need to provide information to describe the available options and the probability of each occurring. For data in categories (which customer, what product etc) this might be based upon historical data or estimates. The main function, RAND(), for generating random numbers gives a uniform distribution over the interval [0, 1].
To turn this into a category or value requires one to calculate the cumulative distribution which varies from 0 to 1. Inverting gives the randomly selected value or category.
In the attached book I show how LOOKUP will do this for a category variable (customer name). To do the same for a continuous price variable you would need a distribution with a maximum cut-off value.
