How Much Do I Earn?
You earn referral fees when a visitor follows a link from your website and makes a purchase from Amazon.com. If you use the classic plan you earn 4% for Amazon and third-party items. Under the Performance Plan the percentage varies from 4% to 8.5%. It depends on the volume of items you have shipped, for both Amazon and third-party items. You can earn up to $25 in referral fees on personal computers, where as referral fees are unlimited for all other product groups. You won't be paid any referral fees on Auctions or zShop items, or items from external sites.

The Performance Fee Structure - Calculation of Fees
By increasing the number of shipped items (these which are generated through your links), the Performance plan gives you the opportunity to earn higher referral fees. The referral rate is from 4% to 8.5% on items both shipped by Amazon or third-party sellers. The following categories are available: Apparel & Accessories; Automotive; Baby; Beauty; Books; Camera & Photo (Consumer Electronics referral-fee rates); Cell Phones & Service (phones only, not plans); Computers; DVD; Electronics (Consumer Electronics referral-fee rates); Gourmet Food; Grocery; Health & Personal Care; Home & Garden; Jewelry & Watches; Kitchen & Housewares; Magazine & Newspaper Subscriptions; Music; Musical Instruments; Pet Supplies; Software; Sports & Outdoors; Tools & Hardware; Toys & Games; Unbox Video Downloads & Games; Video;

Both Amazon and third-party items are added to your total shipped items, on the base of which your referral rate is calculated, and they again are the reason for your higher referral rates. When you move from level to level, the new referral rate will be applied for all the items shipped during the month. If you refer 400 shipped items, you will be in the fifth level, and you will earn 7.50% on all items (Amazon and third-party ones) shipped during the month. An exception is made for consumer electronics.

Here is the chart representing the referral rates in the Performance structure:

Limitations:
Personal computers have their referral fees capped at $25 and Unbox Video Downloads capped at $1.50 per item. You will receive no referral fee on Auctions or zShop items, or items from external sites.