Best thing to do is work out the Gp/xp ratio for cheapest method. All you basically do for example i'll use super attacks, this is assuming you buy Irit (unf) pots (already in vials of water). working out gp/xp is fairly simple, you need to work out the gp going in and coming out, and divine that by the experience you will be getting.. so the formula for herblore is something like this "Ingredients - Finished / XP" In this case it'd be... (Herblore 1st + Second) - Finished pot / XP (Irit (unf) 4,612gp + Eye of newt 8gp) - Super attack (3) 1,176gp/100xp
(4612+8)-1,176 /100
First-Second / XP
4620-1176 /100
3444/100 =
34.4 GP/XP
So making super attacks from unfinished irit pots would be 34.4 gp/xp meaning you times your final xp by that for a rough estimate of the cost. For you that'd be 7.6M for those levels, it's not ideal at this time to train after double xp weekend, you may be better off farming the herbs yourself and buying the seconds off GE it'd take longer but cheaper if you don't wish to spend the money ;) If you use this on future skills to calculate skills like construction you just need to see the xp of a plank and divide the cost into that it's fairly straight forward! :) Hope this helps, Toad