FWIW, Western Union is giving 325:1 (not sure if this is an "everybody but me knows" kind of thing, but hadn't seen WU posted here). Signed up here (I've got a VPN to the US I use here though), used my US debit card (no fees, and they waived any of their fees for first purchase), sent myself $500. The trick was finding a WU that's a "corporate store" as many of the locations listed on the app are affiliate locations, but someone on Reddit mentioned the one on Peru (Peru, San Nicolás 139, 1067 Buenos Aires, Argentina, https://goo.gl/maps/GAJNNMzwh8NvBs1D7) and after a bit of a wait in a long line, walked out with ARS 162,375 .

Yesterday bluedollar.net was at 311, can't complain. A couple of days ago flipped $1400USD at 305 (rate was showing 308 online) with a guy after a little negotiation, wish I'd known about WU sooner.