My wife need to a new car and the C300 looks good for us.
Currently I got a "good" price from a truecar.com dealer online. The original truecar price is 39069 and we have 1000 off discount plus some small dealer discounts. It seems that this is not the dealers' bottom price. I saw others shared their prices in autopriceshare.com and some deals are better(like 36953).

Do I need to continue bargaining with dealers or just take this deal(37869 for C300 4MATIC Sedan 2015)?

You might want to net out the options for any reasonable assessment on bargain/value - new (or used it seems) it's the options that drive the price up in a hurry.

I just purchased my new car yesterday. The final price is $37500 (by cash) and autopriceshare dealer give me two times free maintenance. this is a base model without any packages.

Yeah the options are the key factor in price.

When i was ordering my 2013 c300 in 2012. The leather seats alone was 3k :'( i heard horror stories about the mbtex.

Wait a year and buy the car for half the price. Buying a brand new c300 is for urban youth that live in poverty. I rather have an older model E350 of higher class then spend almost 40k on the most basic Mercedes ever made.

I don't love my car because it screams luxury. I love it because I got it for under $23k with less then 30k miles in 2014.