Why does it take 21 days to get my money ?

[digupatin]

If you are talking about via PayPal it would probably be because you are a new seller.

https://www.paypal.com/au/webapps/mpp/security/sell-saferpayments

[lane-ends]

Becuase ebay does not trust sellers, that is thier default attitude, and becasue they can.

[kopenhagen5]

PayPal - 

Typically, you can access these payments in 21 days or even sooner if you follow good shipping practices. To help get your funds faster, please note the following:

• If you provide tracking information and we can confirm delivery, your payment should be available 3days after delivery.
• If you don’t upload tracking, but mark the item as shipped in ‘My eBay’, your payment should be available 7 days after your latest estimated delivery date.
• If you fulfill the order, but don’t provide any shipping information, your payment should be available after 21 days, as long as your buyer doesn’t report a problem with the transaction.

[foxette-in-sox]

Considering how inexpensive your items are along with not exactly being classed as high risk, I'd

also be asking why.