\documentclass[varwidth=true, border=5pt]{article}
\usepackage[active,tightpage]{preview}
\usepackage[latin1]{inputenc}
\usepackage{amsmath}
\usepackage{pgfplots}
\pgfplotsset{compat=1.10}
\usepackage{tikz}
\usetikzlibrary{arrows, positioning} 
\usepackage{helvet}
\usepackage[eulergreek]{sansmath}

\begin{document}
\begin{preview}
\begin{tikzpicture}
    \begin{axis}[
        width=13.4cm,
        height=10.0cm,
        % Grid
        grid = major,
        % size
        xmin= 40,     % start the diagram at this x-coordinate
        xmax= 90,   % end   the diagram at this x-coordinate
        ymin= 0,     % start the diagram at this y-coordinate
        ymax= 60, % end   the diagram at this y-coordinate
        % Legende
        legend style={
            font=\large\sansmath\sffamily,
            at={(0.5,-0.18)},
            anchor=north,
            legend cell align=left,
            legend columns=-1,
            column sep=0.5cm
        },
        % Ticks
        tick align=inside,
        every axis/.append style={font=\large\sansmath\sffamily},
        minor tick style={thick},
        scaled y ticks = false,
        % Axis
        axis line style = {very thick,shorten <=-0.5\pgflinewidth},
        axis lines = middle,
        axis line style = very thick,
        xlabel=Gesamtausgaben,
        x label style={at={(axis description cs:0.5,-0.05)},
                       anchor=north,
                       font=\boldmath\sansmath\sffamily\Large},
        ylabel=Luxusausgaben,
        y label style={at={(axis description cs:-0.05,0.5)},
                       anchor=south,
                       rotate=90,
                       font=\boldmath\sansmath\sffamily\Large}
        ]
\addplot[
scatter,
only marks,
point meta=explicit symbolic,
scatter/classes={
a={mark=x,red!90!black},%
b={mark=x,cyan!50!black}},
]
table[col sep=comma, meta=label] {data.csv};

\addplot[
scatter,
only marks,
point meta=explicit symbolic,
scatter/classes={
b={mark=*,mark size=4pt,red!30!white,draw=black},%
c={mark=*,mark size=4pt,cyan!30!white,draw=black},%
a={mark=*,mark size=4pt,green!70!black,draw=black,pin=135:{\color{black}$(65, 35)$},label={(65, 35)}] {}}},
]
table[meta=label] {
    x   y   label
    65  35  a
    70  40  b
    60  20  c
};
% \addlegendentry{Gruppe 1}
% \addlegendentry{Gruppe 2}
\end{axis}
\end{tikzpicture}
\end{preview}
\end{document}