Key will not turn locking cylinder. I have the problem down to the cylinder. Understand that I can take it apart and purchase new blades and replace them. Went to Honda dealer, was told I must replace it all, $900.00!!!!! I can do the work but cannot find the parts? Was a radio repairman in the Army and TV repairman for years, now retired

 

You could get the part or the part number from the dealer.
There are online honda dealers selling parts. I don't know which have the best pricing, I'm still somewhat new.
But try this one (search for others)-
https://estore.honda.com/honda/parts...your-honda.asp