@lingchoisan,
You can require IMMEDIATE PAYMENT to avoid having to wait for the buyer to pay.
From eBay's How Immediate Payment Works help page:
โHow immediate payment works
When immediate payment is required, the item's still available until the buyer has completed payment.
[...]
How to create a listing with immediate payment
To create a listing with immediate payment, simply select both PayPal and Require immediate payment with Buy It Now when you're selecting your payment options in the listing form.โ
By the way, just to correct a detail... if you don't enable immediate payment on your items, the buyer has four days in which to pay before you can open a case by selecting Report Unpaid Item, and the buyer has another four days before you can close the case in the Resolution Centre so that the Final Value Fee will be credited back to you. That is a total of 8 days. If you feel worried about having your manga listings unavailable for sale during that period of time, requiring Immediate Payment is certainly a solution for you.
If you feel that your listing is far too cheap, that is your responsibility. (I'm not trying to be unsympathetic, just factual.) You should increase the price of your manga listings to the minimum that you are willing to accept. This is completely in your hands - it is up to you to set the appropriate price.
If you have any sort of proof that it is a competitor who has "purchased" your manga listing without the intention of actually finalising the purchase, you can report that to eBay as a breach of eBay's Unwelcome and malicious buying policy. From that page:
โMembers are also not allowed to bid on or buy an item to disrupt or to leave negative feedback or detailed seller ratings for the seller, with no intention of completing the transaction.โ
However, if the seller doesn't do this with multiple items of yours, eBay may not consider it unwelcome or malicious buying, but rather a simple case of Unpaid Items. You would need to have sufficient evidence to prove your case.
You are probably best off just ensuring that you require Immediate Payment on your manga items, and ensuring that the price is not too low.
You can block buyers who cause you problems or to whom you don't wish to sell, by adding their names to your Blocked Buyers List.
Also, be aware that if a buyer fails to pay, and you open a case and close it without the buyer paying, that buyer receives an unpaid item strike. Many sellers have set up their Buyer Requirements to block buyers who have 2 or more Unpaid Item strikes, so you can feel some sort of satisfaction in that those buyers who don't pay will probably be blocked by a lot of other sellers. Make sure that your own Buyer Requirements are set up to exclude serial non-payers.
