2000 Boxster pukes up o-ring debris

[HVBoxster]

I have a 50K mile 2000 Boxster that recently had cam adjuster problems due to o-ring debris sucked out of the oil sump and pumped into the feed for one of the cam adjusters.

$2000 to flush, experiment, replace a couple cheap parts and get it on the road. Don't know where the o-ring came from and of course that is a concern. Told that the guess is originally green. Has anyone else experienced anything like this?

On a related note, I am now wondering about ongoing maintenance costs with a 12-year old car. I know about RMS and IMS issues. Anything else I need to be thinking about? It seems that it costs $400-500 just to "touch" an engine.

I should add that up until now the only repairs outside normal service items are driver's side window lift mechanism and an air bag sensor replaced under warranty.

Thanks in advance for responses.