Silver Membership

The Wind Waker
You can get the Silver Membership in The Wind Waker, after buying 30 items altogether from Beedle. You get it from Beedle's Shop Ship. Both the silver and gold memberships are acquired by purchasing a lot of items from Beedle.

When you get the Silver Membership, a Complimentary ID is sent to you in the mail.

Phantom Hourglass
You can get the Silver Membership in Phantom Hourglass, after obtaining 20 points altogether from Beedle. More expensive items are worth more points.

A silver membership gives Link 10% off all purchases he makes at Beedle's ships, but not Masked Beedle. Link also receives a Freebie Card. With this card Link can have any item he wants. This is a good way to get one Golden Part.

If Link can get 50 points, he will earn a Gold Membership.