John St., I always look at dolarblue.net, personally. The rate you published, though, is the Cueva rate, not the Arbolito rate.
I get my money from a cuevista who gives me about .10 below the published Cueva rate (depending on how much money I send from the US), and I find that on Florida they will usually go within .10 of the average of the buy/sell difference posted under the Arbolito rate ( today's rate is listed as 8.76 to 9.51). Today, if you push it, you should be able to get 9 - 9.1 from some arbolito on Florida - unless they are still spooked that the cuevas are not offering enough money to them.
I mention the Cueva rate vs the Arbolito rate because there is a bigger difference and often you will find that rate reflected more accurately in what the arbolitos offer.
As mentioned by others, it really depends. For a quick money change instead of making an appointment with my cuevista, Florida works nicely if you know the rate and stick to it. Also, know that the "touts" (the guys mumbling or shouting "cambio") take a portion of each transaction when they take you to see their guy, the difference between what their "boss" will accept and what they talk you into accepting.
The arbolitos will often try to get something below the published lower rate because there are a LOT of tourists walking up and down Florida, but you can almost always talk them up. However, as someone mentioned, the more you seem like a local, the better. I speak nearly fluent Spanish but with an accent probably closer to Mexican than anything else. However, speaking the language helps a whole lot (even with accent), and making a connection with an arbolito gets you even better prices.
If you go directly to the guy who the touts will take you to, you have a stronger bargaining position because you can skip the middleman's rate, although you still have to push.
The more money you change, the better rate you get.
The more you build up a relationship with one place, the better rate you get.
For example, there is a place about half a block off of Paraguay & Florida in a shopping galleria (a travel agency, what else!) that I almost always go to now when looking for a quick change. I look at dolarblue.net, get the average and shoot for about .10 above what the average of their published rates (instead of .10 below the average, because I have a good relationship with them). On my way down to Paraguay on Florida I ask a couple of the touts what they are offering for the quantity of dollars I'm selling and they almost always ask for something below the low dolarblue.net rate. I laugh and keep going and sometimes they'll follow me asking me what I really want. Sometimes they give me a price I like, sometimes not, and I keep on going to the place I mentioned if not.
When I get to the galleria, they know me and I usually don't have to screw around too much to get a good price (I've never found anyone, anywhere, that will just offer me a good price without dickering - if you get a price you think is good and you haven't dickered, you could probably get better).
Last time I went to the galleria was about three weeks ago and there was an old man sitting behind the desk (assuming the father of the guy I usually deal with, the way they interacted) and the guy I usually deal with standing nearby. The old guy asked me what rate I wanted. The price on dolarblue.net was between 8.7 and 9.4. Before I got there, I was being offered 8.5 by the touts down Florida (no one would go above it, it was a strange day) and wanted to sell $2000 USD (special need - I RARELY change that much outside my cueva). I told the guy I wanted 9.1 and he shook his head "no" - according to him the cuevistas were not buying very high (this was after Moreno was told by Cristina to back off money exchanges for awhile, but the cuevistas were still a bit unsure how hard the gov was going to coming at them). The younger guy who I usually dealt with told the older guy it was alright, I was a good customer, and they offered me 9. which, having gauged from the other arbolitos' reactions, I accepted.
Of course, that's still a bargain for them. Everyone knows that after the election the price is likely to exceed 10 fairly rapidly. My cuevista is talking the possibility of 12 around the first of the year. Right now, the arbolitos are trying to get every centavo they can before the price goes up again.
BTW - I see a lot of people all over the place (not necessarily here) using the terms "Cuevas" and "Arbolitos" indiscriminately. For those who don't understand the difference:
Cuevas are the guys who deal in currencies, not just exchanges. Think of them as the wholesalers. These are the guys who deal with bringing money into/out of the country, buy and sell government bonds, etc. They have bank accounts all over the world where people transfer money to these accounts and the guys here give out the money, vice versa, and so on. They are hard to get into - you usually have to know someone who is already dealing with them and be introduced. They are the guys who Moreno and the government usually go after when they want to hold down the Blue prices, except for AFIP standing out on Florida occasionally trying to keep the arbolitos down.
Arbolitos usually work for the cuevas and they are the retail branch. There are surely some independents (I know a guy who works for Nuestra Señora de la Asuncion bus company in Retiro, as an example, and I sometimes use him, but he's not connected with a Cueva and doesn't always offer the best prices) who buy and sell dollars/pesos on a smaller basis, but the bigger operations are almost always branches of, or work with, Cuevas. Florida is probably the biggest concentration of them, but there are a number of places throughout the city that operate as arbolitos.
If you can't make a deal with them to transfer money down from your home country (as an example), you are probably dealing with an arbolito.
