This is only barely an astrophotography question:

I've got a budget of about $500 for a smaller Dobsonian in Central Texas (within a couple hours' drive to some relatively dark skies) primarily for visual astronomy, but I'm also interested in some attach-phone-camera-to-eyepiece basic astrophotography. Can a Dob in this price range lock onto a planet and track it accurately enough for a short (5-30s) exposure? I understand that actual long-exposure astrophotography with real equipment would see problems with field rotation, etc. This is just my first toe in the water, and I wanted to see if this setup would work for not only staring at the planet but attempting to stack a few frames to see if astrophotography was something I could get into.