You could use this for a basic concept, but it will cost less if your reselling everything you make using herblore. However selling potions and such does not give much profit, and the ratio of Costrofit is like Very High: Low.
Super Attack potions are the best if you are looking for cost effective balanced with decent exp. Sell them (3) as people use them to make extreme attacks.
Depends which method you use, expensive methods can cost like 200-400m for 99, cheaper, slower methods around 90-175m to 99. Youtube guides and runescape forum guides i find personally are best.