The main factors in determining a slot machine's value are age, condition and style. Slot machines can be resold to casinos, or to private owners for home entertainment. It is illegal in the United States to use a slot machine for gambling in a private home.
As of 2015, most casinos in the United States use coin-free slot machines. These machines accept bills and print out voucher tickets for users. There are fewer technical issues overall with this type of machine. A machine with fewer technical problems is more viable for a casino to use, therefore a coin-free machine may garner a higher price than one that uses coins.
In general, manual slot machines are cheaper than machines with digital screens. On appraisal sites, such as those run by Rocky Mountain Slots and Gambler's Paradise, prices for manual slot machines in excellent condition range from about $600 to around $900, while digital slots are usually $1000 or more.
If the slot machine is old enough to be considered an antique, the seller may be able to get a more significant amount of money for the machine, assuming it is in working condition. For example, according to Michelle Knows Antiques, a working slot machine from the 1920s might be valued at as much as $2500.