I personally don't think there's a HUGE pay difference. I do have a friend who graduated from SIM and is now doing very well as an RM in CitiGold (related to Citibank). She started off in banking operations in a local bank, climbed her way up (job-hopped a few times), and is now driving a big continental car. She doesn't have a masters degree.
My advice is to find a job first and do master later (when you know more about what you want). But if you can't find employment in this difficult time, then consider doing a master till the situation gets better.