Jase2985: ... a 750w Dynamix costs about $79-99, an equivalent APC unit costs about $700 ...
Assuming that you mean 750VA/500 watts, the APC costs 5 times as much as Dynamix.
DYNAMIX UPSG750 SafeGuard 750VA $125
APC - SCHNEIDER Smart-UPS SMT750I 750VA $608
The only similarity between the two units is the power rating on the label.
Why does a BMW cost more than a Chery?
For the same reasons that an APC costs more than a Dynamix.