Actually, I think a 1/0 or a 0/1 should be worth $2.
To see how the 0/1 unit performed defensively, I simulated a 30 IPC defensive battle:
16 inf attacking and 10 inf defending:
16 inf vs 10 inf
Then I simulated 30 IPC of 0/1 units at $2:
16 inf attacking and 15 bombers defending:
16 inf vs. 15 bmb
As you can see the inf defenders held off the attackers 27% of the time, but the bmb defenders held them off 36% of the time.
So you get a unit that dollar for dollar defends better than inf, but attacks worse (but still is good fodder).
As for the 1/0 unit for $2, it attacks way better than arm, so dollar for dollar you’d be getting a better attacking unit that defends poorly (but still is good fodder):
10 arm attacking 12 inf:
10 arm attacking 12 inf
25 inf attacking 12 inf:
25 inf attacking 12 inf
$2 is a fairer price. $1 is just stupid cheap and would totally unbalance the whole game beyond belief.