The government charges are the same as L-1A: the I-129 fee, the fraud prevention fee, any applicable asylum program fee and optional premium processing, per the USCIS fee schedule. The remaining budget question is how much internal and professional work is needed to document the specialist's special or advanced company-specific knowledge.
The fee is small next to the reason for the transfer
On the government side there is no difference between L-1A and L-1B: the petition fee, the fraud fee, the asylum program fee where the employer's size makes it applicable, and premium processing if chosen, all on USCIS Form G-1055 and all payable by the employer. Professional fees for L-1B may run higher because the specialized-knowledge argument takes more drafting and more exhibits, and a Boischatel employer should ask whether a quoted fee covers a request for evidence if one is issued. Relocation, temporary housing and the specialist's ongoing Canadian obligations are business costs, not immigration costs, but they influence whether the transfer makes sense.
Whether a local worker is available is not a legal test; the file must instead establish the beneficiary's special or advanced company-specific knowledge and the U.S. assignment's need for it.