Hi, i am renting a shoplot that has 18ft high ceiling, going to start renovations soon, it is an e-commerce fulfillment center + shop for customers to come self-collect/demo products. wondering if it is possible or even a doable idea to create a steel platform mezzanine? it's actually a 24*80ft shoplot ground floor that is going to be a warehouse, to oversee the whole operation. Also curious on how much something like below would cost...

yes it is doable and erect according to the relevant authorities' permission.

Consult architect, if it can comply or not. If yes, submit plan. No plan approval, no business license approval ... and illegal structure.
The cost better advised by specialist steel fabricator/contractor.
If you need contact let me know.