Wondering at what volume shipping costs for FBM are lower than FBA fees? I guess turnaround time can be faster for FBM but seems like FBM sellers often have to undercut in order to compete? For example, this listing: https://www.amazon.ca/dp/B0BW7CWTL6 The FBM seller was having trouble getting sales so dropped to 79.99 whereas FBA sellers are getting sales at roughly 89.