  We have calculated ac polarizabilities of the $2 \ ^3S$ and $2 \ ^1S$ states
of both $^4$He and $^3$He in the range 318 nm to 2.5 $\mu$m and determined the
magic wavelengths at which these polarizabilities are equal for either isotope.
The calculations, only based on available ab initio tables of level energies
and Einstein A coefficients, do not require advanced theoretical techniques.
The polarizability contribution of the continuum is calculated using a simple
extrapolation beyond the ionization limit, yet the results agree to better than
1% with such advanced techniques. Several promising magic wavelengths are
identified around 320 nm with sufficient accuracy to design an appropriate
laser system. The extension of the calculations to $^3$He is complicated due to
the additional hyperfine structure, but we show that the magic wavelength
candidates around 320 nm are predominantly shifted by the isotope shift.
