I don't think that you're heating would work, or it would be inefficient at best. If it worked, the material in the center of the funnel wouldn't vaporize at the same rate as the sides. Also the nichrome in toasters is wound into tight coils so you'd have a hard time unravelling those.
For some ideas try
Vaporizer Information Resource Forum :: Index ( there's a vape building section) and look at existing vaporizers. Also keep in mind that you want to be heating the air before it get to the materials (convective), not heat the materials themselves (conductive).
A ceramic soldering iron element (available on ebay) is what vapor brothers style vapes use, in fact the hot glass vaporizer is pretty much a glass encased ceramic soldering iron. Aeromed and some others use halogen bulbs, a few vaporizers use nichrome around glass, and the volcano and supreme vape use heated aluminum (volcano heats them with power resistors and supreme vape with a butane torch).
good luck