Okay, If I understand you now. If you'd like to build a prototype geared to the Greek market? Because if that's the case, I'd recommend a mobile solution rather than a card based solution. Matters not what kind of phone they have, old flip fone, smartphone... The key to making it work is a middle office. You'd have to build that. Where would customers get their BTCs? From storefronts or online via the exchanges? If I am hearing you about your target market we can work out more details...
Well, I wouldn't exactly call them "my market". I don't have the resources to launch a huge BTC promotion in Greece (nor do I have greek contacts), although I am curious; how could you use BTC with an old flip phone?
Also, that would depend on what technology is commonly affordable/available in Greece. Since "not EUR/ECB" is the most appealing feature of BTC for Greeks, delivering the currency to them requires putting it in whatever form is most available to them. I don't even have the slightest clue what greeks commonly use or have.
I'm only interested in that point because it would be nice to see the people of a country outsmart their multi-hierarchal dictators for once, not particularly because I want to profit from the venture.
My question is, even if you load BTC to your smartcard's address without connecting it to your computer somehow, how does the card know how much is on it?
Obviously it doesn't in that case. What I'm proposing is that you stick your card into a machine and deposit your $1, the machine sends a +5 BTC transaction, it gets displayed on the card, and you okay it. The card keeps track of your balance.
For the cards I posted at least, if you browse the site you can see they have cards with keypads as well. It would be possible to manually set your balance with those.
More importantly, how do you set your pin without a central authority doing it for you?
Same solution, cards with keypads. But a pin is not necessarily a requirement, especially when using multisig keys as mentioned. Ultimately a reader is only like $15 anyways so I think your minimum outlay is going to be around $20 regardless of which type of card you use.
Well if the initial outlay for a USB card reader isn't so bad, and you can get a card with a numpad, then you could just input the price they display to you on your card, enter your pin, then hit send. The card signs a tx with only that exact value so they can't change the price after you begin entering your pin. It could be doable but it seems a bit complicated imo. That and, what's the price difference between a USB card reader + supercard with screen and such vs the cost of the cheapest BTC runnable smartphone?