I initially wanted to suggest Linear Algebra from Foundation to Frontiers [1] as it had an accompanying book [2] from Edx, but I had no experience in that, so checked up a bit online and outside their course website, they had not so good reviews [3]. So I am providing the links for you to decide yourself. Another answer on quora [4] suggests Coding the Matrix from Coursera, which is supposed to be rigorous in algorithms with excellent assignments in real world applications. So may be that is your cup of tea.
[1] https://www.edx.org/course/linear-algebra-foundations-fronti...
[3] https://www.quora.com/Which-online-course-for-linear-algebra...
[4] https://www.quora.com/If-linear-algebra-is-so-important-for-...
Since you already took an introductory course, why not just start studying machine learning directly and learn the little linear algebra you need on the side? How much more linear algebra do you really think you need? Don't be a Depth-First-Search learner ;-) [1]
[1] http://math.stackexchange.com/questions/617625/on-familiarit...
Edit: Maths, just study maths. Not meaning to a higher degree, but to enjoy it.
Isn't linear Algebra still taught in high school?
If you want something different, Axler's "Linear Algebra Done Right" or maybe Shilov's Linear Algebra book are good.