It's not
ebay, but rather the US government which still hasn't lifted the trade embargo between the two countries. This embargo has been in effect since the 1960's

The United Nations conducts an annual vote to lift the embargo, but the US has always fought to keep it in place. It is rumored that the US will abstain during the next vote, but this will cause a conflict between the UN and the US Congress, which still wants the embargo. So who knows how many more years this will continue.
I don't think any embargo has lasted this long - just imagine this one was put in place when Kennedy was in the White House!