A petition carries the Form I-129 fee with the L supplement and, if used, premium processing, at the amounts in the USCIS fee schedule, Form G-1055, plus counsel and the cost of assembling corporate and technical evidence. An application under the professions list is far cheaper, but it is only available if the citizenship and the occupation both fit.
Compare the whole cost of each route, including what fails
On paper the professions route wins on price every time, and that comparison misleads if it stops there. The petition buys three things the cheaper route does not: an adjudicated decision before anyone travels, a classification that does not depend on the applicant's citizenship, and a period of authorised stay tied to a corporate assignment rather than to a single job description. Its costs are the published filing amounts, premium processing where a plant commissioning date demands it, counsel's time, and the internal effort of producing development records and services agreements.
The technologist route costs a fraction of that at the counter, but it requires Canadian or Mexican citizenship, requires the work to fit the listed occupation and its own rule, permits no self-employment, and gives a dependent spouse no right to work. For a household with two earners that last point often outweighs the fee difference entirely.