The Purchased Alpha by Hawke Oakley

In a realm where omegas rule, Sebastian is king—almost.
As the oldest brother of three, Prince Sebastian is first in line to inherit the Kingdom of Lacehaven, a wealthy nation where omegas dominate the hierarchy. Sebastian wants for nothing. He has money, power, and beauty.
But he’s missing one crucial thing—a child. Without an heir, Sebastian forfeits his birthright. Fortunately, the monarchy has a traditional solution in place. A plethora of pedigreed alphas, the finest in all of Lacehaven, await his selection. All Sebastian needs to do is choose.
But Sebastian dismisses them all. He wants a challenge. And what the Prince wants, he always gets.
There’s only two ways out of the Alpha Market—purchase or death.
Rourke gave up everything but his last name when he registered for purchase at the Alpha Market. In exchange for his subservience, his younger brother is set for life, and that was a sacrifice Rourke was willing to make.
But Rourke refuses to spend his life as some omega’s toy. He’ll fight tooth and tail to protect his pride, and he’ll be damned if an omega tries to take that away from him.
Even if the Prince himself pays Rourke’s price.