Any other ways to improve your SAT score other than Khan Academy and spending money?

Answered

Some test prep books I can recommend are very good.

1.) All of the College Panda series by Nielson Zhu. (about $25-30 each)

2.) A Critical Reader by Erica Meltzer

3.) SAT Math by Dr. John Chung 16 practice Tests

If you do these books front to back diligently you will see an improvement for sure.

Take one of the official SAT practice tests - there are 10 available for free download from College Board - under realistic timed same as test day conditions. Score your test. Spend the next week or two studying the material for the questions you answered incorrectly. For the reading and grammar sections - Erica Meltzer guide books are very good. For the math there are several to chose from - PWN is one, but there are others as well as many answer explanations are available on YouTube.

Take a second official practice test and repeat the process again and again.

SAT Prep Black Book: The Most Effective SAT Strategies Ever Published Book by Mike Barrett and Patrick Barrett, is also very helpful

If you really want to practise for sat go and try out this free sat practise website with 100+ practise questions for reading, writing and language, maths, sat subjects and multiple full test papers too. You can also find offical papers pdf in this website if you don't want to buy the official sat book.

Go check out cracksat.net .