They're like $820 if you buy both of them from the dealer but if you're going to spend that kind of money Driveshaft shop makes some stronger axles that are rated for 800 hp that cost around $1,100. You could also get used OE axles on ebay for around a quarter of what the dealer charges.
I wouldn't recomend parts store axles I installed some Autozone axles and the shaft was noticeably thinner than that of the OE axles and they felt like poorer quality. From the day I installed them they would squeak when going over bumps and when shifting gears. I also noticed a slight resistance to going into gear in the shifter. Also, I did donuts once in a rainy parking lot and now they creek when going around a turn with any real speed. Maybe other parts stores are better
