When you are doing grid-tied with battery backup, it is going to be considerably more expensive. The costs will be battery, electronics (inverters), a lot more labor, rewiring backup circuits, maintenance...

There are many different ways of connecting grid-tie with battery backup and I believe we are evolving to a place where it will be less expensive in the future, however now it is not cheap. One thing that is making it easier is when you are able to buy all of the equipment from the same manufacturer, so that you are not mixing brands. When you call tech support for different brands, they can always blame the other brand. Also when keeping the brand the same, equipment is better at communicating with each other.

Of course every brand will tell you they are the best!