develop a mac driver

We have an application on Windows which takes images from a webcam and enhances them. On Windows we already have a plugin which looks like a virtual webcam to the operating system and forwards the images from our application to Skype, Google Hangouts or Web browsers. No we're thinking about having someone create the same on Mac OS X instead of developing it ourselves. It would need to be very similar to the (unrelated) application iGlasses ([login to view URL]). We need something similar as provided in this sample ([login to view URL]), however simpler and without any actual hardware access. Instead, the images should be taken from a shared memory location where our existing application puts them. This approach works fine on Windows already. Please give an estimate on how many hours this could take. We would like to do a fixed price project, but don't know exactly what we can expect.