With Apple expected to launch the new iPhone 6 in early Sept., now might be the best time to trade in your iPhone to maximize return.

Ahead of previous iPhone launches, the value of older models has declined by as much as 20 percent, meaning if a user wants to get top dollar trading it in, or selling it, now is probably the best route to take.

Gazelle, a company that purchases old iPhones, says that with the launch day quickly approaching for Apple's new smartphone, the company is urging users to trade-in iPhones now in order to get the best deal.

Current iPhone 5S 16GB models are getting around $290 on the market if they are in good condition, but those prices are expected to drop noticeably ahead of next month's iPhone 6 launch. Even better, Gazelle has announced it is allowing users to lock the price they are selling their older iPhone to the company now, and then send it in to the company once they purchase a new iPhone 6.

The new iPhone 6 has been part of much speculation since a top Apple official claimed earlier this year the company was launching what he believed were the best products from the company in decades.

Senior VP Eddy Cue created much speculation ahead of the Worldwide Developers Conference (WWDC) held in June in San Francisco with his promotion of upcoming products and devices from the Silicon Valley company.

"Later this year, we've got the best product pipeline that I've seen in my 25 years at Apple," Cue said.

The company is expected to launch two separate version of the iPhone 6, a 4.7-inch and 5.5-inch display, Tech Times reports. But it could cost an additional $100 for users, and that has many observers worried that Apple may not be able to get back into the forefront of the smartphone sector if customers are not willing to dole out additional funds for a phone that may not be noticeably better than others on the market.

Apple is likely hoping the new iPhone will help bring back some traction it has lost to Samsung in the global smartphone sector. Consumers are eagerly awaiting what they expect and hope will be a new, innovative iPhone from Apple.