Some thoughts on the PSAT/NMSQT, SAT, and ACT:
The PSAT/NMSQT puts you in the running for a National Merit Scholarship Award (which can be a full ride). If you have a good test taker: DO THIS TEST. (It is given in October on two dates only: a Sat and a Tues). In most school districts, the cost is underwritten by the school, but you have to get signed up in advance (through the school) to take it and to get the underwriting, if offered).
There is also a PSAT which doesn’t qualify you. It’s given at other points in the year.
If you have a mediocre test taker who is college bound, I’d skip the PSAT/NMSQT and do the SAT or ACT. With the SAT, you get to keep the highest score from each section from each time you’ve taken it, so it’s beneficial to retake if you didn’t do well the first time.
Many colleges are stepping away from using SAT/ACT scores as part of their admissions process, because they’ve come to recognize what it really tells you is the socio-economic background of the student, and assesses their ability to take tests.
CLEP gives you college credits (depending on your college — mine only took 12 credits, and only took it if you scored an A. Many CCs will take far more credits and as low as a C). Running Start also gives the uni an external metric by which to measure your student.
The PSAT/SAT/ACT all “count” toward your testing/assessment requirement for homeschooling, so you don’t need to double up on a year you’ve used one of those.