Given the relative size of the model in game, you could probably get away with :
1) A box with a sloped front
2) A box on the side of it
3) A 3 sided tube underneath
4) Ignore the wires
5) Stick a texture on it
It'll be less than a centimetre on screen, even at maximum zoom, so this would look roughly the same as the high poly equivalent, probably in about 30-40 triangles.
Same with the pliers (tool) above, ignore the fine detail on the handle - handles as two 3 or 4 sided tubes, with a block in the middle, with two 3 or 4 sides tubes for the head - probably get something around 30-40 triangles.
It's a shame to simplify them so much, as these models are quite beautiful, but if you look at the digram below, horribly low-poly models would probably be better for the game, with little difference visually.
The models I've just made as example are probably a bit
too far in simplification (and possibly the two ugliest models I've ever made), but if you get the idea of "ignore everything which can't be seen in the game", there must be something in roughly the same area of triangles which would work as well.
The short version is "the model is
too good for items this size".
Is it just me or the texture is 256x256? We've said this like over 9000 times - items may have only 128x128. Anyways - too much polygons.
I think the textures will all be resized, paletted and dithered, so having the source file at a slightly higher resolution isn't going to matter too much - I uploaded most of the things I did with a far higher texture resolution, as it's easier to repair / alter / recolour when there's a few more pixels (and full RGB colour) available, then resize the final one. These tiny items may even want to be as low as 64x or 32x eventually - if the 3D items will also be 3D on the floor (instead of changing to sprites when out of hands), imagine how much difference it could make when someone makes a "Brahmin shit party in NCR" for example.