If you're looking for a cheap, no frills arduino replacement, then the OnStep platform can do it. As it's modular you can build on it. I've made a few of these for my scopes and they are excellent.
For the cheap n cheerful (but still VERY functional) you could go with the WeMos R32 build
https://onstep.groups.io/g/main/wiki/19670
Basic build is around $36 including the WiFi module (you'll need that) which can be controlled via your phone.
You can also add on a GPS module ($10) and build a wireless hand controller (which will be around $50) to make it a portable, stand alone mount. With the CNC shield, there is little soldering and fiddling about.
There are other options to really deck things out with automatic dew heater controllers, focus motors, etc, which will require more study and $$, but sill very inexpensive.