$100 each! Robbery.
I purchased new wiper blades for my 2013 GL450 and they were Michelin, which are OK quality but I didn't like the way they looked different from what was on there to begin with, so I returned them.
Bosch were due to cost $88 for the pair, one is about 26 inches and the other is about 23 inches/ I settled on some VALEO "Silencio" wipers that were pretty inexpensive, bought from RockAuto or I may have gotten the part numbers from their website and then bought the wipers from Amazon. I did remember getting the best quality ones that Valeo makes and since I got a brand new windshield on Nov. 1st, I wanted new wipers to match. The old wipers seemed fine but once off the vehicle, I could see where the rubber had deformed a little bit with age. The new ones are Great! And definitely cost under about $40 for both sides. I remember ordering them separately and got one first, then waited a week or ten days for the second one to arrive, but once that one arrived the swap-out took all of three and a half minutes!
For your 2017 GLS450;
Valeo Silencio 577857 Set Silencio
Front; W/o Heated Windshield Washers; Blade Length: 26" & 23" $29 for the pair.
I've had them on there three months and work perfectly.