I am developing an iOS app that provides educational content, created by professionals (teachers, professors, etc). New content will be added continuously. The number of content editors is limited (just a few people at the beginning).
My question is: how do I pay the content creators? I want them to be motivated to add new content often, but I am not in the situation to pay them a salary.
Paying them a percentage of sales is an option, but then how much? Of course, without content my app is worthless, but without the app the content can't be sold.
Any suggestion is appreciated.
I don't mean to imply you should take advantage of them, but don't underestimate the value of peoples personal desire for meaningless competition.
Maybe at first you should just reward people with "badges" and "digital trinkets", which see, to be common these days. Appeal to the teachers' natural desire to teach and share knowledge. Create a badge hierarchy system where they can earn status among their peers.
Over time create monetary rewards for top contributors or editors. If you pay something like a dollar for every submission you might just end up with the Mechanical Turk problem, where massive amounts of garbage are submitted in hopes of pay.
Its unclear to me how much quality assurance, support and service you are providing for buyers of the content and what value you are creating (besides distribution) for creators of the content. Given i don't understand if you would like to build a distribution channel, create a marketplace, or actually 'own' the IP related to the new content, rather than reinventing the wheel, would try to find the company that has the closest model to yours and make sure you are in the same ballpark.
hope this helps.
You can pay for piece of content i.e. standardize (approximately, of course) various types of content and set fixed prices for it.
This is popular model for paying for content (e.g. that's how Huffington Post/Engadget/TechCrunch are/were paying their editors for posts).
If you do that, the issue boils down to: does the price you can offer can attract content creators of satisfactory quality?
Your situation is unique but in general rule there are far more people out there capable of writing content for your app than there are apps they can write content for, so demand/supply is on your side and the examples I mentioned above tend to pay very little.
You mentioned that you want to limit pool of content creators to small pool of 4-5 but that might be a self-imposed limitation. In the model of paying per piece of content, your best strategy is to setup a reverse auction i.e. let people bid on the tasks you provide. The key for that is ability to clearly define what you expect to get as a final product.
This article http://www.kalzumeus.com/2010/07/17/seo-for-software-companies/ talks about how to outsource content creation (writing, in this example).
Paying a percentage of sales is a terrible idea. First, like you noticed, it's hard to determine the percentage.
Second, total percentage is fixed at 100%. The content presumably must be updated ad infinitum but once you give out all 100%, you have nothing left to offer.
Third, it provides anti-motivation (the income gets more tied to the overall success of the app than the effort of a single content creator which enables e.g. one bad apple to not do any work and profit indefinitely from your effort and efforts of other content creators).