OK, so you choose a phone, and the cost will vary. You'll find it hard, I think to find one under 45 Euros, probably 60-80 should buy you a decent basic phone, though if you want a camera in it, then you're probably looking at a bit more.
The phone itself doesn't affect the Pay as you go tariff, I don't think, so the real question is whether you choose Vodafone or Movistar. Have a look
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