For the time being, they are targeting specialty applications where it is not uncommon to charge in excess of $1000 per meter even for normal earthly fibers.

For scaling up, if one uses the smallest commercial fiber standard (80um diameter cladding--they would put the buffer and whatnot on after it comes back to earth) the mass of the fiber is only 53grams/km so using your $3000/kg the cargo cost is only $0.16/meter which seems pretty palatable to me.