At the same time a fully loaded Falcon 9 uses about $10/kg of fuel to put something into LEO. The cost mainly comes from building the rockets, and to a lesser degree operating them (mission control, landing ships, etc). All of those costs would come down dramatically once you reach the scales nessesary for building such a structure. Economies of scale could easily bring the price down an order of magnitude or more.
For a small-ish cylinder that might be enough. For a cylinder that's multiple kilometers long we would want to do asteroid mining and rockets engineered to bring stuff up cheaply (at the expense of loosing a few rockets, loosing dirt is a lot more acceptable than loosing billion dollar satellites).
For a small-ish cylinder that might be enough. For a cylinder that's multiple kilometers long we would want to do asteroid mining and rockets engineered to bring stuff up cheaply (at the expense of loosing a few rockets, loosing dirt is a lot more acceptable than loosing billion dollar satellites).