I’ve seen better on here. A C-Class is a car that you can find in ex-service loaner status for much less with better miles (like 10 or 12K).
I’d shop around a bit more. If you look in the Trophy Garage, someone leased a 2018 Service Loaner C300 (MSRP: $49,075) for $318/mo (including tax) with first month DAS at 10k/year…and that was here in Denver, where dealers seem to budge less (post dated 2/24/19 if you want to take a look yourself).