Costs depend on whether the employer files a petition or the applicant applies at the border, and on whether a credential evaluation is needed. Use the USCIS fee schedule for current government amounts rather than a figure someone quoted.
Separate government fees from preparation costs
Government charges change, and the reliable references are the USCIS fee schedule published as Form G-1055 together with the current port-of-entry charge. Check both at the time of filing rather than relying on an amount quoted last year. A port-of-entry application carries a modest fee and no petition cost at all. An employer that prefers to file Form I-129 pays the petition fee and may choose to pay for faster processing, and that is normally the employer's decision to make rather than the applicant's. Around those charges sit preparation costs the applicant controls: a credential evaluation, certified translations, courier charges and professional fees. Set the credential evaluation in motion early, because it is the item most likely to delay a start date and the item least likely to have been budgeted for.
Hypothetical example: a brownfield-redevelopment planner receives an offer whose start date depends on a professional licence transfer. The first review should produce a budget divided among government charges, credential work, translations, travel, licensing, and any employer filing expense. Receipts and the current fee schedules settle the numbers; a colleague's old total does not. Price the licence process before choosing a travel date, because it may matter more than the classification expense. A typical error is budgeting only the immigration filing and discovering that a required professional step delays paid work after arrival.