Am also considering a VEPR (limited to 5.56x45 or 5.45x39 here in the PR of CT due to dumb AW law). Would probably go 5.56 so ammo is interchangeable with my AR15.
Have heard the Bulgarian 5.56 mags "usually work" (per RobArms), and now the Polish.
Any sources for both? Have found Bulgarian mags at K-VAR, but no sources for the Polish.