Hello,

I am launching my new patented Spray Mop and Mop Pad Refill products online in a couple of months, and I plan on selling through my Shopify store. Can someone please help me know if I am calculating all of my fulfilment option costs correctly? And which option would be best (I would be renting office space for $700/month for self fulfilment option)

My 2 Products:

Mop Starterkit: 3000 units // MSRP = $35USD
22 x 14 x 6inch box = 14 pounds dimensional weight // $10.50 Amazon MCF fulfilment fee + $0.50 monthly storage // $17-22 USPS Discount Shipping cost

24 Mop Pad Refill: 6000 units // MSRP = $15USD
13x11x3inch box = 4pounds dimensional weight // $5.95 USD Amazon MCF fee + $0.18 monthly storage // $8-13 USPS discount Shipping cost

How are the USPS discounted rates so much higher? Am I missing something?

Amazon rates from: https://sellercentral.amazon.com/mcf?&