This question already has an answer here:
I want to go to Prague for a few days and do there some geocaching. I need therefore SIM card with internet package or internet flat rate. I don't think the traffic generated while geocaching will be more that 50MB a day, so 200-300MB package instead of flat rate would be also reasonable.
So I want to use only internet, only for a few days, I want to pay as little as possible and the SIM card should be relatively easy to purchase (on train station, for example).
What's the SIM card that fulfills my criteria at best?