Well, you could try phoning eBay and discussing it with them, using your attempts at communication as your reason, but I suspect you have a $25 life lesson here.
Put the deadbeat on your Blocked Bidder List.
In future, ask about payment once, and if you don't get paid within 24 hours, open the Dispute and close it at soon as possible. The fastest turnaround on this is eight days, four until the Dispute can be opened and four for the buyer to respond.
You learn something new everyday, whether you want to or not.