When I jettisoned my cromo fork for a NOS coda branded Time fork, it was like night and day how much smoother my bike became. Especially because it was paired with an aluminum frame.
OP, Just pony up the $90 and get a nashbar carbon fork. Unless you're meticulous about checking for cracks and have that somehow already in your preflight check, it's worth buying new. I know carbon's nature of rapid, catastrophic failure scares the crap out of me enough to be weary of used carbon anything. Plus, it seems the catalyst for this is more comfort than weight given the acceptance of an alloy steerer. Other than the fork and a hacksaw blade, you shouldn't have to buy anything. You might, depending on your headset, have to take the old and new forks to a shop to have the crown race swapped over, and the starnut set. If you have a cartridge bearing headset with a slotted race, it will just slide off, and you can do this at home.