There are several things that are needed for a SaaS startup from a legal standpoint:
How can a bootstrap startup do these without spending money on a lawyer initially?
For most startups, the initial focus is make value for your users. So time, energy and money spent on legals is not exactly wasted, but not exactly critical either.
The leading options I've seen are:
There comes a time when you will need more. But for now, spend a few minutes picking your option, and a couple of hours at most putting it in place.