Yes, SIDS is a financial hemorrhoid, and yes it makes gravity and debt stick to your plane for a while, it may dull the pain of Cessna owners to consider this:
when a stock goes ex-dividend, its listed price drops, but every shareholder is effected equally, and no one profits or suffers more than anyone else.
when the price of avgas or landing fees goes up 15%, we all whinge and protest but again, it hits us all equally
when the US $ drops against the Aus $, Australian aircraft owners have all lost a bit of world value on their US made aircraft
Anyhoooo, the point I'm clumsily making is that in say a year, when everyone is either SIDS compliant or their plane is sitting in a kindy playground, Australian Cessnas will be, worth the same as against each other. Also, the market will ensure those planes are more expensive to people entering the market to buy (I sure as hell will be adding the cost of my C210 SIDS to the future sale price, and even if I didn't my bank would do it for me when they repossess it !).
So don't count the SIDS cost as a financial loss on your investment, its an enforced capital gain, even if you don't put a monetary value on having your plane being given a clean bill of structural health. Perhaps you can ponder the value of this peace of mind when next you get hit by a dose of CAT over the wheatbelt on a hot day, or a blast of unwelcome g force when landing at RTI in a howling seabreeze.
Keep the blue stuff on the left flying north from Perth !