best way to keep it is to remove it before you go to the shop. The ones I worked at never charged more if the core was missing or if the converter was gone... But tell them you want to keep your old one and then they will want to charge you...
Generally you can recycle them at most places that recycle aluminium / brass / copper since the converters value is in the exotic metal inside.
and since you post publically your political views. I disagree, While hate isn't how I feel, I do see the national debt rising at record rates, and the dollar declining in value at a similar inverse proportion. I see needless programs and moneys being spent foolishly ~ Not that the opposing canidate would have been a better choice, But govenment needs to change. I think a flat tax and term limits would be a great start towards recovery from political corruption. The kicker for me with this administration is the Helth care bill
... I HATE the new healt care bill and think they were foolish to push it thru congress. Unless it is repealed or gutted you will see changes unlike any you have ever seen in your 44 years.
Most recently ~ With this bill it looks like big business now LEGALLY has the option to dump ALL employer provided healtcare coverage and just pay the government's fines for a 75% cost savings on a BILLION $$ + liability. What corperate fat cat would sit idle and watch his competitors take the lead on saving thier company 75% on a billion + liability. I thought we were promised we could keep our current provider.