The “I” to inspect the fluid, simply means to check of the level of the fluid - not change it or flush it. Checking the oil is easy. Checking the coolant level is a look at the overflow tank when the car is cool and add 50/50 mix if needed. Checking differential and manual transmission mean putting the car on a lift taking out a plug in the side of the case and adding the correct fluid until the fluid drips out of the hole. Brake fluid is something you change every 3 years regardless of miles on a car with traction control and ABS. On a 30K car that is one to 2 years old you don’t need to do anything with the brake fluid and the other inspections should be cheap.
You don’t need to spend $600. If the car has an automatic transmission it could be a wise move to change that fluid. But, make sure it is the correct fluid, a CVT auto transmission takes a completely different fluid than a conventional auto transmission. It is a common mistake to use the wrong fluid and the result is a severely damaged transmission. For this reason I’d prefer having a Subaru dealer change the auto trans fluid just to avoid this type of major error. Some Subaru’s have a CVT transmission and others don’t in that model year - so an error is possible and needs to be avoided.