Schrecks are not broken because spammable mainline inf has access to them IMO. The problem is that they require almost zero micro.
Instead of changing upgrade costs or weapon stats, I would change the way you have to use them.
My idea:
Keep shrecks on volks (90 mu).
An upgraded squad doesn't get a panzerschreck as weapon that takes up a slot BUT as an ability.
- cooldown similar to PzFausts (perhaps slightly shorter)
- slightly higher range than PzFausts
- 100% accuracy when fired
- no muni cost since you have to upgrade them for every squad individually
That would effectively reduce the range of shrecks (something a lot of people have asked for because it is supposed to be a defensive weapon), remove annoying RNG, increase the reload time for shrecks AND add a little more required micro (no more a-move).
Basically, OKW would get buffed PzFausts that don't snare. But they still use shrecks so it's unique