More effective, and mana efficient, magic starts to become available in act 2 (especially shaman magic).
Trading just reduces purchase prices.
The link worked when I posted; the site/domain must have just expired, or is having DNS or other issues (I'm getting different errors depending on the browser I try).
Here are some direct download links for the guide in
high (60MB),
medium (44MB) or
low (30MB) quality (though even the 'low' quality one is still good quality, if space or bandwidth are an issue).
