Is it permissible for a woman to travel for trade without a mahram, but with a group of women, given the high cost of a mahram's ticket?

A woman is not permitted to travel without a mahram, and this is supported by the authentic Sunnah. If the presence of a mahram is obligatory for the Hajj pilgrimage, which is one of the pillars of Islam, then his presence is even more essential for business travel. The high cost of a ticket does not constitute a necessity that permits travel without a mahram.