No. You don't necessarily have to replace the MC and brake booster at the same time. They are independent unless you learn that they are both bad. There are tests that can be performed to point you in the direction of which is bad. The Haynes manual does this and I'm sure the Helms does too.

Here's a little motivation for doing the work yourself. The MC is fairly straight forward. Depending on your model, you maybe able to rebuild your existing MC. The dealer quoted me about $400 (including the parts and labor) to replace it.

The brake booster is not the same. They recommend only buying a new one or one that has already been refurbished as it is not a job for the normal person. The dealer quoted me about $800 for the brake booster job. Now maybe if you had the work done at the same time you might could come out a little better, but yeah, you're right, I doubt it.