Dear eeCA;
To be more "Marketable" you should thoroughly understand your market. Presuming you wish to work where you live now, I would spend time going to Trade Association meetings, reading trade journals and communicating with others in the precise field you wish to work in. You have to discover what skills are in demand and how your present eduction addresses that.
You may discover that recruiters in your area cant find enough Masters of Engineering to meet demand. That would be a clear signal to sign up for more school, but I think finding how your existing skills meet existing needs is more important. An employer who needs your experience and wants to keep you will be more motivated to pay something toward your future education.
A useful place to visit is your local business development office, they can tell you about local industry that is expanding and hiring. Then you narrow down your search to firms that use your skills and training.
Why not try calling an Engineering Dept. head at a local firm and try setting up a meeting to discuss your situation. Some senior managers will be receptive to this, it shows that you have a genuine interest in the company, rather than being another addition to their pile of resumes.
I'm not an Engineer but these are all things I have used in the past and still use today. Hope it helps.
Best of Luck !
Adrian D.