Today
Buy: 1 USD = 13.75 ARS
Sell: 1 USD = 13.95 USD
Prices should go up quite soon, probably as of next month. There will also be rises in public utility bills (which in Buenos Aires are still extremely subsidised - my natural gas bill is 3 USD per month) and that will necessarily impact on prices as well.
That said, probably by March or so prices should stabilise.
I was on the phone with Amex Argentina yesterday on another subject and they told me the new conversion rate will reflect on anything bought from today onwards.