Czechpoint gets $6.50 for a VZ mag spring. And they show in stock.
Not bad if that's new compared to Cope's. But yea, unless you can combine an order the shipping makes that as much as a surplus mag.
I spent some more time with my Vz mags w/AK springs, Loaded & unloaded them each six times. I did notice that one of them would stop at 29 rounds, but only did it once.