When I do practice problems and practice tests I usually use the calculator on my laptop since it's accessible. I know the SAT doesn't let you use computers during the test, but I don't have access to a good calculator to bring with me on test day. How important is a having a calculator and what are some of your suggestions for good, cheap, and permitted calculators?
Technically, all problems on the Math section of the SAT can be done without a calculator, but it's helpful to have one for checking your answers, graphing functions, and doing calculations more efficiently. Taking the test without a calculator will put you at a slight to moderate disadvantage compared to other students, so I'd definitely recommend bringing one. Take a look at this page for more info on the SAT's calculator policy as well as a list of acceptable calculators: https://sat.collegeboard.org/register/calculator-policy.
If you're looking for an inexpensive calculator, this site posts the best deals for calculators online. You can get a used graphing calculator for pretty cheap (I saw a few that were only $20-30). Just make sure you check the list on the SAT calculator policy page first to make sure it's an approved model.