Depends on the reason for your low GPA...if you've got very good reasons for a low GPA, strong MCAT score, and excellent activiites..it may offset your GPA!
If you ahve the money to throw around..then go for it! Never hurts..especially if something about you adds diversity to their class.
I had a 2.8 Undergrad GPA (I know its no excuse but it was aerospace and mechanical engineering). I attended a post-bacc program at Hunter College and got 3.9 GPA and my overall jumped to like a 3.1 and my BCPM was a 3.4. Also got a 31P on the MCAT. Along with crazy volunteering and extracurriculars and I was invited to an interview at Einstein and already got accepted into a couple schools. So if your heart is in it and you show them you have the mental capacity to handle to rigors of med school, a low undergrad GPA can be offset.