fargle: I'd say keep the black instead of switching to the silver on the back of the head. Make it look something like a single piece helmet, with the tribal-esque patterns cut out. As vermine said, 5-10k.
sprytryne: Transparent heads don't generally go for too much, since they don't work well with non-shaders. That one seems to be a bit random - I'd put it at 1k at most.
The emboss on the second looks way overdone.