With the official announcement of Apple’s iPhone 6S just around the corner, Gazelle today announced limited-time promotional trade-in pricing for the iPhone 5s, 6, and 6 Plus, guaranteeing that Gazelle’s cash offer will “beat the trade-in credit offered by a customer’s wireless carrier or Apple.” The promotion applies to U.S. carriers AT&T, Verizon, T-Mobile and Sprint, as well as Apple’s trade-in program.

Gazelle notes that its Best Price Guarantee pays out in cash rather than credit, one of the strings often attached to carrier and Apple trade-in programs, and covers all colors and capacities of the aforementioned three iPhone models. Notably, the company says that it will beat any better offer customers find at Apple or their carrier through September 9th.

As noted in our guide to trading in your iPhone to buy a new iPhone 6S, Gazelle’s pricing system does an atypically good job of considering factors such as excellent device condition and factory/carrier unlocked status during trade-ins. The promotional pricing runs from today through September 9th, the day of Apple’s event.