  The temperature dependent resistivity of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ (x =
0.23, 0.25, 0.28 and 0.4) single crystals and the angle dependent resistivity
of superconducting Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ single crystals were
measured in magnetic fields up to 9 T. The measurements of temperature
dependent resistivity for samples with different doping levels revealed very
high upper critical fields which increase with the transition temperature
monotonously, and a very low superconducting anisotropy ratio
$\Gamma=H_{c2}^{ab}/H_{c2}^c \approx$ 2. By scaling the resistivity in the
frame of the anisotropic Ginzburg-Landau theory, the angle dependent
resistivity of the Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ single crystal measured with
different magnetic fields at a certain temperature collapsed onto one curve. As
the only scaling parameter, the anisotropy $\Gamma$ was determined
alternatively for each temperature and was found to be between two and three.
