Victor wrote:

That's an interesting question. There has been some talk about using
carbon nanotubes (CNTs) to create a space elevator, but unless the cost
of production for CNTs decreases a great deal, this will not be a
feasable option. I believe CNTs costs are on the order of $1000/kg.

last time I look for this was 100$/g probably now they are around to 50$/g.

$1000/kg would be a very good (for now) price tag for industries and
enought to start build the SE.

Mirco