Does not recommend this product
As someone who has run a boostrapped eCommerce fulfillment center for the past few years and worked across most industires - we also do FBA Prep, subscription boxes, kickstarter launches, etc. I'd love to better understand the economics of this. We tried doing a flat-rate (not $1 but low) and it didn't work at scale. Clients abuse storage, clients needs change, etc.
I hope this works out - it'd be revolutionary if it does at scale but I can't imagine how from the outside.