I have an absolute steal of a deal here. Never used, MASSIVE data, and ready to go regardless of the country.
What condition is the phone in and does it have a clean ESN?
It is brand new. Never used. and yes. 100% clean ESn
Well I looked up the ESN and it's actually a bad ESN. You might want to double check that. Since it's a bad ESN it's only worth like 300. Will you take 300? 
Not a chance! I'm unsure where you got your data but this is a new/unused phone. ESN is perfectly OK.
I beg to differ, you must have bought the phone from some shady characters. It says right here your ESN is bad. I'll give you 300 final offer.