The quality DCC motor and sound decoders are all around or under $200. This will be less than your digitrax and Phoenix combination.
In the USA I recommend Zimo, less hassles programming, good support and a wide range of sound files, plus a rugged quality decoder that handles G scale dcc voltages. I would check with Train-Li for decoders.
As a backup I would recommend ESU.
I would not recommend Massoth in the USA, poor support and known goofy programming problems.
The Zimo have support for "smoke unit direct drive", where an inexpensive but great puffing smoke solution exists, that keeps you from paying $200 for a smoke unit, you can use an old Aristo or USA Trains unit, often available used for $25.
Greg