Is wallapop trustworthy? Is it too good to be true?

I recently downloaded this new app and i wanted to know if it was a good idea? I found this deal where it was a brand new iphone 6, unlocked, 64 gb with the charger and headphones For only $175. The guy says that if i accept he will send an invoice thorugh email and then ill pay and he'll send me the phone and he won't get the money until i receive my phone. I don't know if i should trust it?

NO.
IF ANYONE WANTS MONEY BEFORE GOODS BEWARE.
WOULD YOU GO INTO A STORE AND SAY HERE IS MY MONEY BEFORE YOU HAVE BOUGHT ANYTHING.
WHEN YOU GOT TO THE CHECKOUT THEY COULD SAY WHAT MONEY.
BESIDES, UNLOCKED PHONES ARE NOT BRAND NEW. IT JUST MEANS THEY HAVE BEEN USED AND SOMEONE HAS TAKEN IT BACK TO BASICS. SISTER CAN DO THIS WITH LAPTOPS AND SHE NEVER SAYS THEY ARE BRAND NEW.