Don't know about the Bosch, Rob at Needswings has the NGK Irridium IX plugs in 2 heat ranges for $82.95 a set.
I put the normal range plugs in mine, no problems for 2 years now. Climate here about the same as yours.
The DS front plug is easy to access, if you are gonna replace all 12, then I'd recommend unplugging the coil packs and removing the valve covers.
Your hands will thank me, plus you can get a torque wrench on them. ( 21 ft/lbs )