Reasons why you shouldn't alch:
1. It's slow as fuck. 65K xp/h at the best
2. You almost always lose a bit of cash
3. Lots of better methods
Alching is a good way for 10hp pures, anyone else should stun, plank make or string jewelry. Stun alching is faster xp/h but costs a bit more too. Plank make profits on mahogany but is more clicking, yet fast xp/h. Stringing jewelry costs around 3gp per xp I think.