It's definitely worth it to build the inline heater. It's customizable with the heater you want and it's cheap too (PVC isn't too expensive). The only thing to make sure to do is get aquarium safe silicone and let it cure before using it. I used GE Silicone I i think? It's the one without mold inhibitors. You don't want mold inhibitors.
oh yeah, i already read about which silicones are safe. i think i got GE too because it said 100% silicone.