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I have a number 7 (picture related), got it 10 years ago and still in good shape, carbon blade, easy to sharpen. I also have two n°8, one in my car with Inox blade, for eating and another with carbon blade in my bag for all king of stuff (screw driving, opening boxes, ...).
They cost from 8€ to 15, depending of the blade type, and handle craft or wood.