The BOP Engineering helmets are a guaranteed skillup, so I made one for both my mainspec and one offspec (the latter got me from 449 to 450).
If Saronite weren't cheaper than toilet paper, I might have made a third one but since it is I didn't.
The knives aren't DE'able, they're of common quality. I was selling them at 5-6g per in February, but the market returned to normal shortly thereafter. Otherwise I've just given them away to friends and to their alts and to random newbies running around in Ironforge.
Unfortunately flint and tinder appear to be going away in the next patch, according to the current patch notes, so their limited value to non-engineers is about to get worse, making it difficult to even give them away to strangers on the street. /cry