The insurer typically charges a one-time filing fee, commonly in the $15 to $25 range. That is separate from your premium and separate from any reinstatement fee the Nebraska DMV charges, which the DMV publishes.
More detail
Three different numbers get conflated in this question. The filing fee is the carrier charging for the administrative act of transmitting the certificate, and it is small. The reinstatement fee is set by the state, is the same for everyone in the same situation, and is published by the Nebraska DMV rather than estimated by anybody else. The premium is the actual cost of the insurance, and it is where essentially all the money is. When somebody says an SR-22 is expensive, they mean the premium on a flagged record is expensive, which is true. Keeping the three separate is useful when comparing quotes, because a carrier waiving a $20 filing fee while charging $400 more in premium is not a better deal.