Heres your answer to that question on the 2006 Insight.
there is going to be 2006 Insights produced/built Etc.
My suggestion is to "Wait". and purchase a 2006 instead of paying a premium for a 2004 Model.
Your only talking about a couple of months.
BTW; If you really want a 2006 Insight you will have to go to the Honda Dealer of your choice and place a "SOLD"
order and your Honda Dealer will then go to his regional Sales Rep. and place a sold order to him and his (Regional-Sales-Rep.) will then place the order to Honda and they will then build the Insight. The time frame your looking at is around Two-Months/Maybe-Six Weeks once the Sold order goes to Honda.
This is not my opinion but fact, I have already been there and went through the process with the Honda Dealer that is next door to the Dealer that I work for. This was a 2005 Insight,Red,Manual, w/A/C.