First find the total number of times the cost is halved: 30 years / 10 years/halving = 3 halvings
Then halve the cost once: $1,000,000 / 2 = $<<1000000/2=500000>>500,000
Then halve the cost a second time: $500,000 / 2 = $<<500000/2=250000>>250,000
Then halve the cost a third time: $250,000 / 2 = $<<250000/2=125000>>125,000
#### 125000