The difference between Spycraft and WoT is substantial.
WoT contains nothing (except the chanelling system) that you couldn't easily create in D&D. As psion put it, it's re-warmed D&D. Bleh.
Spycraft took the system by the horns and rewrote practically everything, and made it COOL.
WoT: Channelling Magic System, new base classes, new prestige classes
Spycraft: Mastermind system, skill criticals, Chase system, completely re-worked combat system, unique automatic weapon rules, action dice, gadget and budget point system, new core classes, core feat concept, new prestige classes, TONS of new feats, feat categories, etc.
WoT is nothing more than a D&D rehash.
Spycraft is a completely new GAME, and one that, in many ways, I feel is superior to D&D.
BTW, as for not having $ costs on gadgets, it makes sense. You can't buy them. If you could, they'd have astronomical prices because of they are so far past the tech curve. Giving them a $ value doesn't work.