I have a possible job, where I will be adding a sub to a Zinsco main breaker. I see three different ways to do this:

1) I can double-lug the main panel feed (with the appropriate lugs) and have my 'main breaker' for the sub-panel in the new panel;

2) I can buy a new ETL (non-UL) Chinese breaker; or,

3) I can buy a 'reconditioned' breaker on-line.

What would your choice be? Why?