Hell no! And don't believe them if they've said they've paid. I would also consider blocking Nigeria because while you do get the odd genuine person, if they are buying stuff on eBay, it's generally a scam. Don't do it. 

If they haven't paid, sit tight for 4 days and open an unpaid item dispute. Then close it 4 days later. Doing that will ensure they can't leave you feedback. Then block them!

Can I assume the buyer has 0 feedback?

Edit: You'd also be taking a huge hit with postage too. $41 with SOD for a parcel to go to Nigeria. Way more than your standard $18.