Apple is yet again on the verge of releasing their latest batch of newest iPhones, and what that means for most folks is that their old standbys are now outdated.

Although not all iPhone owners look to trade in their units as soon as a new one is available, some still do opt for that route; and in such cases, getting fair value back for reselling an old unit can help greatly in making a new purchase.

First off, people should know that if they do indeed have plans of trading in their old iPhone 5S, 6, or 6 Plus, now is just about the best time to do it, according to Apple Insider.

The week before the actual introduction itself typically is the best timeframe for people to get the most money for their older iPhones, and they really shouldn't wait around too long to do so.

Unsurprisingly, payouts for old iPhones in the first three weeks after the big announcement of a new unit typically yield about 15 percent less value, making that a particularly bad time to consider a trade in.

Now that the timing of the transaction is ironed out, there's the matter of where to trade in the old iPhone.

One of the leading options for iPhone trade ins is Gazelle. Gazelle has already announced a Best Price Guarantee for units such as the iPhone 5S, 6, and 6 Plus that will be traded in before Sept. 9, according to Mac Rumors. Gazelle's guarantee means they will do better than the best offers coming from Apple and major network carriers.

Next Worth is another company worth considering for an iPhone trade in. The company reportedly offers more money for the iPhone 6 and 6 Plus than Gazelle, so they could warrant a cursory look as well.