Bash plates are way over priced in my eyes.
I reckon it cost me $40 - $50 to knock up my sump guard out of 3mm plate, held on with 4 bolts, 2 front, 2 rear all going through holes already existing in the chassis, all bolt heads recessed.
The transfer case guard was a fair bit more involved. Lots of measuring and testing. Time wise it was expensive, but money wise, again, only about $40 - $50.
I haven't worried with a gearbox guard, the box is up out of harms way. Won't be fitting CV guards, I reckon you stand a higher chance of getting something stuck in there and ripping a CV boot if you fit them.
Maybe a tank guard??? But if you dent that, then you have your fuel tank sitting and rubbing on the dent, which I reckon is worse than leaving the tank as protected as it is when it comes out of the factory.