Here are some of my Ideas of how it could be done:
If there is an option to display items stats via the api this could be used to verify a transaction. So it could be possible to sell a specific item without the hassle of typing in it's stats by hand and it is certain that the item is in fact in the possession of the seller and later the buyer.
The site could act as a trusted party receiving both the payment and the fee plus some collateral. There could be some reward system which reduces the fees after each successful transaction.
If that is not possible we could pay highly reputable members to act as trusted party receiving both the item and the payment. That should also be fully EULA proof
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If all fails we could still use a standard feedback system which isn't entirely fraud proof but hey, it works for everybody else!
I would also suggest not implementing the ebay style timed auctions but a conventional strike system where the seller can decide when to close the auction or let the system do it automatically according to criteria. This could be time, number of bids, amount, the slope of bid increments or even some combination.
If anything it would be an exercise and a hobby project.
You speak the truth. Sadly, this is true for most businesses/projects in Bitcoin
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We are mostly involved in niche markets which are inherently tied to hobbyist projects. That isn't necessarily bad.
At the end of the day, this is just an idea that goes nowhere until someone with the proper skills puts in the time and effort to make it a reality.
If I were a web developer and programmer, I'd do it myself
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Well the only languages I am somewhat fluid in is C, Pascal and Basic, from school and some toying around with applied math.
I would be willing to learn myself a more suited language if that counts, I find go very interesting but haven't gotten around to get a working dev environment with it.