It's been 22 years since I last took the SAT, but only 12 years since I took the GRE.
I took an SAT course in High School. No idea how much it cost. My advice? Skip it.
Buy the Barron's book (or whatever better versions may exist now) for preparing for the SAT and WORK AT IT. I did that for the GRE and SMOKED IT. If it worked for me for the GRE five years after my last academic course, it WILL work for you for the SAT while you're still taking classes.
Good luck!