BDB is right, the most economical way to play rolls is to find a used player piano, buy it, and then fix up whetever is needed. I have seen working player pianos for $250-$2,500 in my local market, but you may have to take some time to find one in good working order.
The old upright player pianos of the '20s were made about 4-6" deeper than non-player uprights. This was to accommodate the roll player mechanism. As such, it's often not possible to retrofit a roll player stack into an upright that wasn't designed to be a player piano.
Do you specifically want to play piano rolls? You can convert most upright and grand pianos to a player piano with a modern solenoid-based player kit, such as PianoDisc, Pianomation, LX, etc. Prices range from $5,000 to $10,000 installed. A hefty chunk of change, but the modern systems are fully "reproducing" player systems with expression. The LX is regarded as the best of these systems.
Most player pianos are not capable of dynamic expression except that which is controlled by the pianolist. There were some expression systems (DuoArt, Welte-Mignon, AMPICO), but these are rare today and very expensive to restore. For what it costs to restore one of these, you could likely acquire a 5'-6' grand piano and put an LX in it.