>>11221513If your focus is math and physics, you'd probably want to start out with a general physics textbook and a calculus textbook.
My university used Physics for Scientists and Engineers by Knight as the general physics textbook, and Stewart's Calculus seems to be the modern standard for an intro calculus textbook.
Just buy older editions, no reason to drop $200 on a book.
If your focus is math, the post-calc 2 curriculum is generally differential equations, multivariable calculus and vector analysis, and linear algebra in no particular order. I think it would be a good idea to learn these along with the MIT open courseware videos and then find a textbook to supplement for problem solving exercises.
If you want to learn more physics, buy Taylor's Classical Mechanics and Griffiths E&M and QM. No clue what books are good for higher level fluids and thermodynamics, haven't studied those yet.