Inert wands are crossed with 1 of the essences to obtain a wand that discharges that element. As far as I could tell, the different types of inert wands is irrelevant as to the quality of final wand....so why they cost differing amounts is unknown.

Crafting wands is random based on the crafter's level....initially it is no bonus, +1 int or +1 cons; by level 8 (I think, it could be 10) it is random with no bonus, +2 int or +2 cons.....it gets to +3 but I have only verified that at level 20, so not sure how quickly it happens......crafting wands is def op, but as most won't take the time to craft it is a great perk for those who will.