You are free to attempt to negotiate a lower lump sum payment, or a monthly payment plan with the creditor. However, given that the creditor has now expended time and money to get a judgment against you it is likely that they will not be willing to enter into an agreement with you when they can take a portion of your paycheck,or collect based on their judgment in other ways.
You absolutely have the option to negotiate for a smaller sum and pay monthly. I have no idea if your creditor will be willing to enter into that type of agreement, but you can certainly try. Whether or not your creditor will be agreeable to that will depend on a variety of factors, including the creditor's internal policies, how much they are able to garnish from you each pay period, and what you would propose to pay them on a monthly basis. It doesn't matter that the creditor actually went forward with obtaining a judgment against you; it can still settle for whatever the parties agree on.
Many creditors will be willing to enter into those voluntary agreements; it's a bit of a hassle to garnish someone's bank account/wages and payments need to be made to the third party doing the garnishment, making it take longer to get full payment.
A better bet is settling for a lump sum payable within a shorter time period- typically around 90 days or less. If that's possible for you, of course.
And you may want to consider bankruptcy. Typically, when someone is to the point of being garnished, bankruptcy is the best option.
You always have the option to negotiate a post-judgment debt, but many creditors will demand a lump sum payment near or equal to the full balance. If the debt amount is significant, or you have other debts you'd like to be relieved of, you might want to think about calling a local bankruptcy attorney for a free consultation.
Please note that the above is not intended as legal advice, it is for educational purposes only. No attorney-client relationship is created or is intended to be created hereby. You should contact a local attorney to discuss and to obtain legal advice