Is getting a master degree worth it?

I've got a BS in Environmental Science and ten years of experience, but I have not been at all happy with the Env. Industries jobs and pay. Is getting a master degree worth the time and money? Also, what majors are lucrative? My interest lean toward possibly teaching at the college level (yes I'm aware that you need a PHD to teach at the college level) , or further my science background. Any advice would be great. I'm also 38 w/wife and kids. I really need to get into an industry that pay's better than 50K/year. Thanks.