I went to Uruguay last weekend, I bought a 300mb which lasted 30 days and cost 90 ARS. I was there for 8 hours and got through about 230mbs. 3G internet speed in Uruguay puts argentina to shame.
They also had some cheap voice plans which I didn't buy since I wasn't planing to talk to anyone who didn't have FaceTime...In the end I received 2 calls, each under a minute, and made 2 calls of my own, one for just under 2 min and the other for 6. Bill for that came to $50 + Iva, which is expensive but not absurd.