Does your iphone use a SIM card ( dunno if US iphones do as most US phones are rubbish and use a pay card rather than having a SIM card ) .. if so you could see about seeing if you could buy a pre-paid data SIM card in France. Note that the rules about charging for data in the EU are far more regulated/fairer than in the US. A 20MB european booster for my UK 3G phone is only about USD 8.