They are called retaining spring clips and excuse me to say that for something that regularly needs to be removed to place the car in the service position, are probably the worst designed POS on the entire car! Difficult to remove/install, need 2 people and trying not to damage the clamshell
End of rant. Maybe Ben006 or someone could improve this design.
As ar as used coil packs I wouldn't hesitate to use from Woody if he says are good! Or search eBay and Quality porsche to see if they have a low mileage set. I've bought parts from both and have been very happy! Good Luck!