[lien]

icon and fitness manufacturers do make accessories to their standard equipments. also, the thing is that they already have an installed base at gyms. these companies have a large software team and they will be able to eliminate you over time if they decide that this is big enough of a market to enter.

there are industry alliances out there whose single task force is to standardize protocols of how to make it easy for devices to get online. the current model is using the iPhone/iPod as a remote control to get these devices online so it's not that hard. this means even if your app is better, it won't survive for now, but long term it might not if the only true innovation is using image processing to capture data.

Yes, there will be people who will not want to shell out the money to buy these expensive devices. but that means that you are targeting a population who "do not want to shell out the money". You don't really want to build a device where cost is one of your biggest value propositions.

the last idea - I actually really like the idea of targeting healthcare rather than fitness. I actually want to see family members of these patients pay money to track their progress and see what doctors are saying. Doctors are more likely to pay so that they can get access to their patients' data and monitor their patients' progress over time. and yes, partnership is a big thing here because you want to focus on software innovation. by partnering up with hardware companies, you could benefit a lot from them.

there is also a company called Dossia where they keep track of health records. definitely a good partnerhsip to have some time down the road when your product is ready. it's founded by andy grove from Intel, all of my friends who are Intel employees get them for free. I don't know what type of info they keep track here, but if you allow doctors to update info into these health records, then it'd be really useful...now this product sounds really exciting to me! good luck!!