It is your right to have an abortion pursuant to guidelines set out by the US Supreme Court under Planned Parenthood v. Pennsylvania. That is, the fetus cannot be viable (moving in the tummy) - Basically the same as Roe v. Wade.
Let's suppose you are Married with three children and your husband wants you to abort the fetus because he cannot afford another child. If you abort under the legal guidelines - no problem. In effect, your husband is paying you to abort.
Therefore, it is not the payoff that is illegal. Rather it is whether you abort legally (second trimestor).
By the way, if you choose to abort for this dummy, make sure you hit him up for many, many thousands of dollars. If this stud makes big buck, you are better off having his baby and hitting him up for hefty support which could amount to hundreds of thousands of dollars.