There are some pricy (and awesome) motorized slider solutions out there (we quite like the Syrp Genie), but they are all kinda expensive. Anything with decent controls (screen/app) is 500$ or upwards. What if you throw some creative thinking into it?
Videographer Nitsan Simantov constructed a variable speed slider motor from a TurnsPro – a $99 egg timer style panning device (kinda like the Genie Mini we reviewed, but $150 cheaper). The idea is to use the TurnsPro as a push/pull device. Connect a piece of string to the thread of the revolving head and tie that string into the slider cart (this is why this built rang a bell with the Syrp Genie).