just do 8k firestrikes if you can pick up 16k airs at 20 ea and 8k minds at 20 ea, that'll be 480k if you just buy 22k minds at 20 ea, that's 440k it's a 40k difference for saving almost 3 times as much time if you can pick up airs at 10-15 ea, then you'll even be saving coins x_x not to mention you get exp per damage too
Armors and weapons can be relatively cheap in RS (Bronze/Steel/Iron/Mith) if you want to buy a full suit of steel armor in real life, you'd better get your wallet out.