Kodi, I would get a decent 1/2" drill to mix with. I have an old Dewalt that I have been using for 15 yrs, I paid $80.00 for it and it still running like a top. I do a lot of tile and I wouldn't spend the money for a Protool or Festool. I use my drill to mix concrete as well as thinset and it takes a real beating. After a while the stress of mixing has made the drill have some serious runout. It's fine for mixing but you can't drill a straight hole in anything else but mud! Plus the drill is sucking up cement and concrete dust every time you mix which would shorten the life of your drill. They also have dedicated tools just for mixing thinset that are stronger and easier to hold than a standard 1/2" drill with handle.
Cheers
Curt