(Apologies for the spam-magnet)

We're off to France in a couple of weeks, and I'm looking for a French data SIM that'll fit in my existing Huawei E353 dongle. I've got an existing PAYG data SIM from Three, but I don't really want to pay roaming charges for data-only.

So far I've found £50 for 2GB, which seems pricey. Is this standard? Or do you guys know where I can get something cheaper?

One condition is that I need to buy this in the UK, and have the option of topping it up with a UK credit card, because -- once we're in France -- the wife isn't going to let me go shopping in whatever the French equivalent of Carphone Warehouse is, even assuming that there's one near where we're staying.