Well, I'm currently on 80 mage, and I'd like to get it up a bit more, to 94 or 96. :P

 

 

 

But I'd like some options, such as the fastest and most expensive way and cheapest and slowest way - and, IF possible, an estimate of time taken would be nice. :)

I've heard that enchanting diamond bolts gives good exp and *maybe* a profit. (don't quote me)

 

 

 

Alching is always an option but it's usually only cost-efficient if you make the runes or alch items yourself.

Enchanting air orbs is slow but very profitable. You can either make or buy unpowered orbs, enchant them, and then either sell them or attach them to battlestaves.

Stringing jewellry is extremely fast, it took me only two or three days to get 83-89 magic through stringing. However, with the terrible economy right now, it is verrrrry expensive, i'd suggest waiting for things to settle back down before attempting this.