As I understand it, taxis are cheaper going to EZE than going to the centro. That's because the taxi companies have to pay for a booth at EZE. There's a taxi booth labeled 'taxi ezeiza' and they charge $98 flat-rate however when I was there last (a couple weeks ago) they had no taxis available so instead of waiting 30 minutes, I hired a remi from 'world car' booth in the international terminal and paid $115. I also took a cab today from Recoleta to EZE and it cost me $80-flat rate. My taxista asked me if I was given a price when I called for the taxi and I told him '$80 mas or menos'. He then turned off the meter and just charged me a flat $80 which I think is about right, mas or menos.
If you're travelling solo, a cheaper option is taking a bus through Manuel Tienda Leon. For $40 you get a bus to their main terminal in the Capital and for $5 more, they will take you to a specific address (hotel, apartment, etc.) after transferring to a Remi at the bus terminal in the Capital. Pretty reputable company, I recommend them. I wouldn't worry about booking in advance, there has always been plenty of room.
If you're travelling solo, a cheaper option is taking a bus through Manuel Tienda Leon. For $40 you get a bus to their main terminal in the Capital and for $5 more, they will take you to a specific address (hotel, apartment, etc.) after transferring to a Remi at the bus terminal in the Capital. Pretty reputable company, I recommend them. I wouldn't worry about booking in advance, there has always been plenty of room.