Iphone unlock question

Yes definitely. If you sell a locked phone, your buyer will have to go all the way to unlock it themselves. However, if you do it for them already, they would be able to use it once they receive it. Thus the value of an unlocked phone is definitely higher than a locked one.

Its the same actually for JB iPhones sold. Those iPhones with clean installs and jailbroken will fetch a higher price because some people simply just want a jailbroken iPhone out of the box without the hassles of jailkbreaking.