By Sam Oliver

Published: 11:00 AM EST

If a survey of developers attending Apple's Worldwide Developers Conference this week is of any indication, the average cost of a third-party iPhone application will fall well below $3.00, with the vast majority being made available at no cost at all.

Piper Jaffray analyst Gene Munster, who appears to be the Wall Street analyst making the best use of his invitation to the annual conference, took some time Monday following Steve Jobs's opening keynote to chat with 20 Apple developers mingling amongst the crowd of 5,200.

He found that 50% of them were in attendance because they plan to focus solely on developing applications for iPhone and iPod touch, while the remaining 50% are doing the same in addition to writing software for Macs.

In a surprising revelation, half the iPhone developers said they were authoring what Munster calls "Enterprise apps." Specifically, the analyst said 15% of the apps will tap into the iPhone's location-based services, 10% will be entertainment oriented, 10% will specifically be video games, and another 15% will be other Enterprise-level apps.

"We see this as a positive indicator of the potential for Enterprise adoption of the iPhone," he said. "We found the average cost of iPhone apps on the App Store to be $2.29, with 71% being free."

This startling stat may alone explain why Apple has started to encourage developers to consider charging for some of their apps in the future. The company will receive 30% of the revenue from all applications sold over the App Store to help offset the costs of marketing and operating the download service, but won't receive any reimbursement for operational costs associated with serving up free software.

In speaking to iPhone developers, Munster also discovered that 70% of them have written applications for other mobile platforms, but approximately the same percentage of their iPhone-bound apps will not be made available for rival platforms.

In particular, those developers pointed to the iPhone's standout feature set, which will drive unique applications that cannot easily be ported to software on rival mobile phones.

"Ultimately, we believe this creates added value for the iPhone over and above other mobile platforms," Munster said. He added that all but one of the developers surveyed said that the iPhone developer tools made application development easier than they had expected, with the majority going out of their way to praise Apple for providing the most intuitive and easy to use mobile development platform they've ever experienced.