Money is certainly important and I would say that depending upon location and industry, an ME would start at about $60K plus benefits (e.g. medical, retirement, etc.) which are not to be underestimated, especially as you grow older. For experienced MEs, depending upon the industry and what you are doing, $250K+/year is not unheard of. But, equally as important as the money is the ability to "grow" in your profession. Being an ME, there are numerous different career paths you can follow depending upon your changing needs and interests. Which brings up the portability of your skills. Once you are an ME, you will not be limited by geography or industry as there is a need for MEs in many if not all parts of the country (and world) doing all sorts of things. You can go into design engineering, field engineering, application engineering, project management, sales, training, consulting - the list is quite long. At one time or another, I have been all of the proceeding and have worked in the US as well as several foreign countries. The key is to keep learning and trying new things and being an ME enables you to grow and opens the door to doing many interesting and even exciting things. As well as making a good salary. So while a good salary is important, the profession of Mechanical Engineering in and of itself is very rewarding in the experiences you can have and the people you will meet. It may be hard to put a dollar value on all of these "soft items" , but to me, they have been worth a lot.
Hope this helps to answer your question, good luck.