Second what V to the B is saying. If this thread is about the cost of traps and making them as PCs; there I cannot help you. But if you think about using them as a GM, I'd strongly suggest using them in conjunction with other threats.
Consider a room with a CR 1/2 Acid Splash trap. It spits out a small gout of acid on someone who trips the Trigger; big deal. Now imagine that the ONLY way to go is through the Trigger, and that the only monsters in the room are a kind of Ooze that's immune: acid. Suddenly this trap becomes a serious nuisance.
Traps are good as ways to divide larger encounters. One toe-to-toe fight with four mites and a giant spider is a CR 3 fight and pretty challenging for your APL 1 party. The same fight as 2 mites and a shallow, easy to detect pit (call the pit a CR 1/2 and it deals only 1d6 damage) is merely a CR 1 fight but unless the PCs disable the trap, eventually it opens releasing a giant spider from behind. It works out to the same CR but splits it into 2 separate encounters.
Finally, think about WHY the trap is there in the first place. Most traps have the CHANCE to kill their prey outright, but also slow or immobilize their quarry making it easier for the hunter to finish off their kill.
Consider a kobold outpost with a Burning Hands trap. Now first off they'll have a way to avoid the device; a secret way around or over it, magic or genetics to ignore the fire damage, etc. Secondly, any good kobold adept or sorcerer knows that Burning Hands at level 1 just simply doesn't do enough damage to kill much more than a Tiny sized rat. One thing a flash of fire DOES do though is ignite things.
So... Burning Hands trap; within range are some fire crackers, wicks sticking out of the walls. Trap goes off, the wicks burn, and POP POP POP! Suddenly the kobolds know you're there and one round later they ambush you from inside the walls.