Who will pay for it though? I doubt Ethiopia is in a condition to build a large wall to keep them out. They seem to be the ones that really have problems with Somalis when it comes to a proper border.
I heard that China is having $3 trillion worth of forex reserves. Perhaps China can help Ethiopia. In return, Ethiopia can permit Chinese resettlement in the eastern Ogaden region, which is mostly populated by the ethnic Somalis.
You propose to sell the country for money? This is nonsense! How to trade territory? What will be left for the children? In addition, such relocation may lead to ethnic conflicts in the future.