Factory brake booster question

Do some diagnostics first. It might save you some dough. Check the big vacuum hose at the booster to see if it's getting vacuum. Remove the check valve, hose and all out of the booster. Hold your thumb over the opening in the check valve and have someone start the engine and see if you have vacuum there. Sometimes those check valves go bad. If you have no vacuum there, pull the check valve off the hose and try the test again. If you now have vacuum without the check valve, your check valve is all that's bad. It's entirely possible the booster is bad. But a simple test that costs nothing isn't a bad idea.