Program officials say the slots will still generate considerable revenue for the state.
Maryland is paying more than double for each slot machine that officials acquired to fill the state's first three casinos.
The Washington Post found the state is paying about $10,000 per machine per year. At the current rate, the paper says the state could spend $50 million a year more than projected by the time all five privately owned casinos are open.
The state launched its slots program in 2007. Maryland is one of only a handful of states, including Delaware, where slot machines are purchased by the state and not casino owners. The idea is that the state is responsible for the integrity of the gambling.
Program officials acknowledge the added cost but say the slots will still generate considerable revenue for the state.