You can add a refugium to just about any tank. Just depends on the size you want and space available. If you want it inside the cabinet or a hang on. That whats great and difficult at times about the hobby.
There are a few threads on new to the hobby and what to consider. The major item is budget. Red Sea makes great stuff, but it a bit more expensive. If you have more room in the budget over the tank and cabinet, then that's fine because you will need it for rock, and other equipment.
Do you have to have a all in one tank? If you want a sump below you will have to drill a hole or run a line to a tank below. Are you up for that? If you get a tank already drilled for a sump that would be easier, especially just starting off.