i have got one spanish orange sim through ebay, works great...100mb/1eur. throughout EU and when mb's are used you simply get charged another 1eur. for 100mb more
you can topup the sim here starting from as as little as 5eur.:
https://neos.orange.es/neostopup/top...s?reqCode=init
in some EU ountries orange (france telecom firm) has also 4g/lte roaming agreements.