We recently had the same thing happen to our 2006 G6. The dealership quoted us $3500 to replace a arms, struts & brakes. My husband found this assembly on amazon: 12 Piece Kit Strut Coil Spring Tie Rod Sway Bar Control Arm Ball Joint LH RH Set...for $290.
He also ordered brakes: (5 Lug Only) Approved Performance G22456 - [Front & Rear Kit] Performance Drilled/Slotted Brake Rotors and Carbon Fiber Pads....for $160.
And wheel bearing & hub assemblies: Sixity Front Wheel Bearing & Hub Assembly 2005-2010 Pontiac G6 Pair Left Right Driver Passenger Side.....for $65.
He did all the work himself & then we took it to the shop to have an alignment done. All together with parts, taxes, alignment etc, I think we ended up spending about $800 total to do it ourselves.