Crafting Magical Trap Cost

[Splendor]

Automatic Reset Trap costs:
+500 gp × caster level × spell level
+Material component costs × 100

Do you pay 1/2 this (as crafting magical items) or the full cost?

If so a teleport trap costs
500*5*9=22,500

and would take 45 days to complete? (500 gp/day)

Is there a spellcraft DC check involved?
Could you increase the DC by 5 to halve the time?