The lowest level trap spells are level 14 and are 25 AP each (75 AP for all 3).
If you start doing adventures at 20th and get 1 AP/adv, it would take 75 adventures to get the spells (with no failures)!! Assuming you would make level 24 within 75 adventures (quite reasonable), that means you would be trying to get the next set of spells (148 AP for those 3!) before being able to get the low level ones.
At level 26, you would get 2 AP/adv, etc. How does one ever manage to get the lower level trap spells while they are still low level characters?
Spell AP costs need to be reduced.