First If you buy the template, you can make your own clothes.
If you decide that your pants will look very similar like my pants I am offering here (and pants usually look quite similar), you still would need to animate them for each frame & do the paperdolling yourself, save the spritesheets etc. which is a lot of work.
It's certainly much more work, than what this add-on pack costs and provides in terms of quality and comfort, but the decision is up to everyone on their own.
If you want to put in the hours on your own and as long as you don't resell it (general guidelines), there is no step I'd take.
I am happy if the normal add-on helps people. I just seperated them to keep costs down for people who really just need the characters for prototyping.