There are a number of variables that affect how much you payincluding:
Type of product: non-media, media or oversize.
Type of sales channel: Amazon.co.uk, internationally or another channel.
The fees are made up of:
Per-item fee
This is a flat-rate fee of £0.75 + VAT (unless you’re a Pro Merchant in which case you pay £25 + VAT per month).
Referral fees
These range from 7% to 15%, with one exception: Amazon device accessories (e.g. Kindle accessories) clock in at a breathtaking 45%.
Variable closimg fee
These are also flat-rate fees that range from 14p to £1.15, but are only levied on the following: books, music, DVDS and VHS videos (do people still buy VHS videos?).
Fulfilment fees
These are the fees Amazon charges for picking, packing and posting. They are most affected by the size and weight of the item.
Storage fees
Amazon also charges for storing your FBA stock. It charges per cubic foot (as opposed to weight). This is worth bearing in mind, particularly if you’re selling light but bulky items. Infact, these charges can be ruinous if you have a static stock.
A-Z of Amazon 