My understanding of the duty tax is things manufactured here or could be manufactured here where taxed heavy not because of luxury but competition potential.
If you own the company that sells the items you can deduct the GST that is also attach to it but no other breaks I know of.
heads up they charge GST on shipping cost as well.
every time I get a box of equipment from outside of Belize I feel at the end of the day I paid for it twice.

White Sands Dive Shop
https://whitesandsdiveshop.com/