I use Lebara Mobile (UK), it is a very good service to which i have no problems with.
But unless i'm mistaken or their website incorrect to use GPRS abroad would cost me £307.20 a MB
Just out of interest has anyone else found daft prices like this with other providers?
(Source)
http://www.lebara-mobile.co.uk/en/roamingtariffs.php
GPRS International Roaming: £30
(per 100Kb of international data transferred)