Have you read the Buyer Guide at all?

What are buying limits?

A buying limit means you won't be able to buy any more items until you complete your current purchases and orders.

If your buying activities have been limited, it may be because:

• You're new to the site, and are making a lot of purchases or buying expensive items
• You've suddenly and significantly increased your bidding or buying activity
• You have an excessive number of unpaid items or cancelled orders because you didn't pay on your account
• You're the highest bidder on a number of auctions, but haven't paid for any items yet