Zamak MRL cost: 10k
Zamak MRL rearm: 5k
M5 Sandstorm MLRS cost: 22k
M5 Sandstorm MLRS rearm: 11k
Both the Zamak MRL and the Sandstorm are completely the same apart from the faster driving speed of the Zamak MRL and better armor of the Sandstorm. But buying and rearming the Sandstorm each costs more than twice as much. Even just rearming the Sandstorm costs more than buying the Zamak MRL itself.
Prices should be adjusted in my opinion.