I go to Roho -- I used to go to the one in Caballito, but they just opened on in Palermo at Malabia between Nicaragua and Soler I believe, they are are in the 1700 block. They are expensive, but really really good. They do their color with a cap, not painting it on etc. Their cuts are fantastic. I usually get a cut every other time, and if they offer you extras (conditioning treatments etc) ask the prices. For color, cut, shampoo/conditioner, bano de crema, brushing, and a little product (everything, and I mean eveything is a la carte here, down to the dollop of wax they use at the end etc) I paid, and I hate to admit it, 300 pesos (GASP! yes!). When I don't get color, and just go for a cut, shampoo, blowdry, it's less than 100.
I never thought I'd be willing to pay that money for my hair here, but the cuts are great. I can go up to three months without having to cut it again, and just do colour in between -- you know you got a good cut when it looks good that long.
In Palermo: Ask for Diego -- he does everything, color and cut
In Caballito: Dany for cut, and I think the guy I had for color was Rafael, but I can't remember, I only saw him once.