40-52 is a good range, but I would recommend going with Granite Crabs. It is MUCH less costly as compared to RS gold the alternative Bull Ants, and its quite difficult to acquire the marigolds to use for Bull Ants. To get Granite Crabs all the way you'll need 4,010 blank pouches, gold charms, iron ore, and 29,050 spirit fragments. This can cost anywhere from the high 600k's, in the 700-700k range.
52-55 you will make Spirit Terrorbirds. Consider keeping these pouchesbecause they will help you a lot. 2,220 blank pouches, gold charms as well as raw bird carcasses and the 30,000 spirit shards needed. This number is a bit of a lot, but it's not too bad. Take a look at tip.it 3. Best of luck to you, and I hope that I could have helped.
Right now as my setup for mage, I'm using the Helm of Neitiznot (Acctually gives a slight magical attack and defenes bonuses and prayer). A long-lasting Staff/Drag Dag, P++ or Whip (They aren't able to buy RuneScape gold decrease the magic attack bonus plus I like to cast by hand while holding a melee wep to ensure I can keep the spell in place and then DDP++, Specify them or simply whip)