The rear bushings frequently wear out they are difficult to see. You can get them on eBay for around $150 each; labor is about 45 minutes each. They are not magic, just a few bolts and a 3/4 inch torque wrench. You can "borrow tools from big box stores. The $300 is inflated; GM charges $203
If a mechanic noticed they need to be replaced ASAP, I don't know what you could wait for? the front end falling off?

 

LCA replacement isn’t that complicated, here is a how to

https://www.chevyhhr.net/forums/how-...ol-arms-44378/

 

So, folks are saying that the Chevy HHR needs the cast lower control arms and not the stamped version. What is the best way to tell the difference when ordering the parts? Part number? Would especially not want to order off Ebay without a reasonable assurance of ordering the cast version. Are aftermarket good for these parts or it is important to get OEM GM?

 

Moog, AC Delco , Delphi, they list part numbers and material they are made of.
RockAuto,

https://www.rockauto.com/en/catalog/...trol+arm,10401

1AAuto

https://www.1aauto.com/2009-chevrole...09-1153?page=4