Why would you want to pay $70 to rent a phone that you could buy and keep for under $50? I went and priced Greek prepaid SIMs. You can get them for E19.90 which includes E8 of airtime, which is about 25 local minutes. If you talk more than that, you can buy more airtime credit.
All European countries use GSM 900/1800 phones, so a phone that works in one country will work in all of them. They all are caller pays, so as long as you have a SIM and phone number for the country you're in, incoming calls are always free to you, although rather pricey to the caller.