How about this; write up a simple web page in php or something with approximate costs for each item...
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Let people "build their own PDA" and see how much it would cost. Let them save their option in a cookie, and gather statistics when they 'save'. You can get all kinds of good info from that, including most often chosen options, and average/mean/median cost.
Yes, I have though about that and the best marketing research tool to do is called "Conjoint Analysis". It would provide you repeatedly with two randomly mixed products, sum up the price and let you state your preference. From all that it calculates the most preferable model and the relative preference of features.
I yery much like the idea of "Open Source Product Sepcification", so if you would volunteer to write the scripts, I would try to provide some data to fill it in.
Unfortunately, the whole approach works only if you have really the choice to design a device from scratch.
In this case it can only work the other way around: use an existing device and add something which is most urgently needed to make it attractive.
Nikolaus