How do you figure Pathfinders + Seeker Missiles is 150 points?
In order to get the missiles you need some sort of platform, so either a 150 point Skyray or placing missiles on every other vehicle you buy. That still costs points. All for a weapon where you need to hit with the markerlight before you can even fire the seeker missile. You've basically given the enemy a 4+ save before you even fired.
I really love the idea of the seeker missiles, but I really can't see how they'd be consistently useful. Tricks like using them to fire at rear armor from a Piranha after moving fast are one thing, but they don't seem reliable enough to make me want to drop suits in their place.