On page 246 of the 3.5 DMG it states that the market price of a Wand of Fireball(Caster Level 5) is 11,250 gp. Assuming the market price is the same as the base cost, I would divide that number by 2 to get the cost to create it(5,625 gp) and divide by 25 to get the cost in XP(450).
However on...