neither ebay nor paypal set the  sellers timeframe for payment...... the seller does

4 days ???? pffffft

http://pages.ebay.com.au/help/pay/require-immediate-payment.html

Requiring immediate payment

As a seller of an auction-style Buy It Now listing or a fixed price (Buy It Now) listing, you have the option of requiring a buyer to pay immediately with PayPal before that buyer can purchase your item. (4 days???? pfffft)

You might use this feature if you're selling a time-sensitive item or if you want to avoid unpaid items. This feature is only available for PayPal payments.

The helpers will say who would accept a paypal payment for a car or a boat ....................me......... those registration transfer papers will beat an australia post docket any day regarding delivery.

Last car I sold and accepted paypal the fee for the $2400 was $88 odd dollars

OP there is a tab at the bottom of every page entitled site map if you click on that and then select a to z in help topics there is plenty of info there to help you more understand ebays policies

From what I can see the info that has been supplied above more related to what is the "norm" on ebay and does not actually pertain to what the policies say....

Ebay makes no differentiation in their policies in a local pick up buy it now as compared to a buy it now that needs to be posted regarding the commitment that has already been made by the buyer sight unseen. (link please)

In fact ebay includes in  its user agreement a clause that states

 YOU ACKNOWLEDGE AND AGREE THAT EBAY IS NOT INVOLVED IN THE ACTUAL TRANSACTION BETWEEN BUYERS AND SELLERS. (then how could ebay set any payment time limits, remember and I quote"it's ebays playground)

AS A RESULT, EBAY HAS NO CONTROL OVER THE QUALITY, SAFETY OR LEGALITY OF ITEMS OR CONTENT POSTED BY MEMBERS ON OUR SITE, THE TRUTH OR ACCURACY OF LISTINGS, THE ABILITY OF SELLERS TO SELL ITEMS OR THE ABILITY OF BUYERS TO BUY ITEMS.

WE CANNOT ENSURE AND DO NOT GUARANTEE THAT A MEMBER OR BROWSER OF OUR SITE WILL ACTUALLY COMPLETE A TRANSACTION OR ACT LAWFULLY IN USING OUR SITE.

and advice on the help section like.......

You need to be at least 18 years old because eBay is available only to individuals who can form legally binding contracts under applicable law. If you are not over 18, you can use eBay only in conjunction with your parents or guardians.