My team bought two 12V lead batteries and this motor

https://www.robotmarketplace.com/products/0-me1003.html

Does anyone have any suggestions for a controller and input system?

Alltrax controllers have always been a popular choice.

https://www.ebay.com/itm/Alltrax-SR48300-Motor-Controller-for-EZGO-TXT-1994-Up-Golf-Carts-Series-/391699078056?mkcid=16&mkevt=1&_trksid=p2349624.m2548.l6249&mkrid=711-127632-2357-0

You'll need a 5k ohm resistor type throttle. There is a pedal type or twist grip available.