Nets are ranged weapons. Ghost Touch is a melee only enchant. That may not work the way you want it to.It already did. Good catch though, it probably should have cost more as a custom enchant to get a melee only property on a ranged weapon. This game is played at the beer & pretzels level, and it would have easily been approved anyway.
There are already Ghost Touch Nets published, so you were probably not too far off : )
Ghost Touch also works on ammunition in addition to melee weaponry.
On topic - Quickened True Strike + rod of Cancellation might serve as a good deterrent, at least against other humanoids. Sometimes they tend to care more about their gear then their well-being - and even if they make the Will save, the rod is not spent until that +5 Sword of XYZ is gone ^^
Elemental gems that have been souped up to Summon monster 9.