I enjoy the STAR magazine - there are some good technical articles in each issue. If you just want the magazine you can call and order copies of back issues.
They will also send you a complimentary issue - the current one. The STAR comes with the membership.
If you like to attend club functions, talk with other MB owners, attend club rallys, and occasional tech and mechanical workshops - it is well worth the $45 a year. You can also receive a discount at most dealerships and other MB parts places by providing them with your membership number (I think).