How much would it cost to make an iPhone app with a GPS locator?

It should cost you somewhere around $7,000 - $10,000.

There are many ways to develop an iOS app at affordable price. Below are the estimated costs:

• Simple, table based app – $1,000-4,000 – you provide all the content, clear direction, and example apps of what you want it to do. If you know your way around Photoshop, you can probably supply the graphics which will cap this project at $1,500. The additional costs are when you want to GPS locators, Social media integration or bells and whistles like that.
• Database App (native) – $8,000-$50,000 – Again, you provide every piece of content, image, writing, sound, etc. The cost is going to come from creating the logic within the app and architecting all the usability and/or game play. The content will usually be dropped in and then parsed accordingly. These projects tend to be front heavy since the data is what’s driving the entire game and the framework is so important.
• Games – $10,000-$250,000 – The hardest to ballpark. As a benchmark – I’ve heard Angry Birds cost anywhere from $125K-$180K to develop (although they were pioneers). Talking to some developers who are into the hardcore game source code (render, sound, maths, physics, etc), many of the racing games will that use the gyroscope will be $125,000 without even blinking – and that’s just for the code. Even if you try to keep it hyper simple, games get complicated quickly. Hooking into game center, having top scores, and integrating with an online community can be tricky. The benefit of a game is that they download in much greater number. As a marketer, there is nothing more viral than a fun game, which is something to keep in mind for your ROI. Ask yourself: how much do I need to spend to make a “fun” game? That’s only something you can answer. Interested in learning how to develop elite apps? Checkout the post How To Develop an App Like Angry Birds.
• Additional Includes – See below – here’s a quick list of additional functions you may want to add into your current app:
• In-App Purchasing – $1,000-$3,000 – this allows for users to buy new content or full versions of the apps. The cost spread comes from the amount of in-app purchasing, the complexity, and whether or not you build it all into the first app or if you are doing it from a server.
• Web Services – $1,000-$5,000 – This is taking the content to a remote access point so that you can update your app with an XML files instead of raw code changes. The degree to what you need varies but I would recommend having this conversation with your developer before getting too deep – it can save you HUGE headaches down the road.
• Game Center – $1,000 – Apple’s done a good job at making this integration easy with the SDK. As long as you keep the numbers clean, you should be able to integrate easily.
• Share Capabilities – $500-$1,500 – This is mostly for social media (twitter, facebook) and emailing, but there can be other integrations. WordPress websites, for example, may be one. Lots of options and most of these platforms have robust APIs to make it work well.
• SDKs and like Chartboost – $50-$200 – SDKs are an extremely important part of tracking our apps and making money off them.  Generally you can get any SDK integrated for relatively cheap, but the more specific you are with your SDKs, the more expensive. SDKs that you may want to include are:  Google Analytics, Chartboost, Applovin, Xplode, AdMob, and Tapjoy.