No
It would help cover the cost, but not cover it.
You can probably get between 400-500 in the BEST circumstances. I get 300 per 5s- I don't sell directly to consumer, though.
Figure out your costs- how much you would pay, how much they are selling for, and what you get after fees.
Correct me if my math is wrong but on swappa, I see that the price of last sold iphone 6 was $770. Considering it might take some time between 2 to 3 weeks, I can maybe sell for at least $700? Note 4 on Verizon for full price is $699 so wouldn't that cover the cost besides $199 that goes into buying the iphone?