Would this be a good idea?

I want to know. About how much would 90 herb cost from around 60? Also, how much would barraging rock lobs from 94-99 cost? Also approx. how many charms would i manage to obtain through this method? thanks alot for your help!

Edit: Would it be wise to get 95-99 prayer or just get 90 herb?

 

94 - 99 what?
Herb depending on methods could cost anywhere from 70m - 200m
If you do prayer potions its 46m.
Need to make 57k prayer potions currently only a loss of around 800gp.

 

What other skill can barraging possibly be? Obv its magic lol.

It's around 100 crims p/h I think, you'd need to find out on average how many barrages it is p/h and how many barrages it is til 99 though