http://www.rerundomains.com/domain/eritrea/er.php offers domains from many African countries including Eritrea. There are several others such as www.101domain.com and www.rwgusa.net that look like they intend to offer domains from Eritrea but their pages still say that IANA has yet to delegate an adminiistrator even though IANA itself says it has done so.
I too wanted to register a .ER domain. I have just sent an e-mail to Eritrea Telecommunication Services Corporation asking them if I can register the domain and how much would it cost.
Well, I did receive a REPLY only not the kind I was looking for. It was a FAILURE DELIVERY SYSTEM, automatically generated by Gmail. It seems that the e-mail doesn’t exist anymore, the one provided on IANA.