If your motivation is just to add a line to your resume, a Masters degree is very expensive. Unless you are going into a field like education, where specific certifications and degrees are required, you can probably use your directly related experience.
The following may be obvious to you, and if so, I apologize for stating it. I'd recommend first looking at the job(s) that you want and what employers are asking for in terms of education and experience in the job postings for those positions. Figure out where you meet or exceed those requirements and where you fall short. Then you can decide what education to fill the gap. You may find a professional certification, an MBA, an executive MBA, a masters or bachelors degree in another field, or several well chosen seminars, classes, or web based learning provide the best alternative.
For myself, the MBA early in my career was a way for me to become well rounded in business and gain the confidence to break into management. It worked well and was well worth the investment in time and money.