  Multiple recent studies have identified the metallic antiferromagnet Mn$_2$Au
to be a candidate for spintronic applications due to apparent in-plane
anisotropy, preserved magnetic properties above room temperature, and
current-induced N\'eel vector switching. Crystal growth is complicated by the
fact that Mn$_2$Au melts incongruently. We present a bismuth flux method to
grow millimeter-scale bulk single crystals of Mn$_2$Au in order to examine the
intrinsic anisotropic electrical and magnetic properties. Flux quenching
experiments reveal that the Mn$_2$Au crystals precipitate below 550{\deg}C,
about 100{\deg}C below the decomposition temperature of Mn$_2$Au. Bulk Mn$_2$Au
crystals have a room-temperature resistivity of 16-19 $\mu\Omega$-cm and a
residual resistivity ratio of 41. Mn$_2$Au crystals have a dimensionless
susceptibility on the order of 10$^{-4}$, comparable to calculated and
experimental reports on powder samples. Single-crystal neutron diffraction
confirms the in-plane magnetic structure. The tetragonal symmetry of Mn$_2$Au
constrains the $ab$-plane magnetic susceptibility to be constant, meaning that
$\chi_{100}=\chi_{110}$ in the low-field limit, below any spin-flop transition.
We find that three measured magnetic susceptibilities $\chi_{100}$,
$\chi_{110}$, and $\chi_{001}$ are the same order of magnitude and agree with
the calculated prediction, meaning the low-field susceptibility of Mn$_2$Au is
quite isotropic, despite clear differences in $ab$-plane and $ac$-plane
magnetocrystalline anisotropy. Mn$_2$Au is calculated to have an extremely high
in-plane spin-flop field above 30 T, which is much larger than that of another
in-plane antiferromagnet Fe$_2$As (less than 1 T). The subtle anisotropy of
intrinsic susceptibilities may lead to dominating effects from shape,
crystalline texture, strain, and defects in devices that attempt spin readout
in Mn$_2$Au.
