The total budget cost will depend on the exact set up. One Lutron SmartBridge can support up to 40 Lutron devices, and their auxiliary switches (the pico remotes) tend to be noticeably less expensive than the auxiliaries for the Z wave devices. So if you have any three-way switches in your set up, the Lutron Caseta and the GE, for example, and up costing just about the same plus maybe an extra $30 to cover the cost of the starter kit that has the SmartBridge. And the Lutron are better engineered devices. But if you need only master switches, then the GE will be significantly less expensive. So different things work for different projects. 
The SmartThings hub includes a Z wave controller and a zigbee home automation (ZHA) coordinator built in, so if you buy switches using one of those two protocols you won’t need an additional bridge.
The device class features FAQ includes more discussion of what options you might want to look at. The light switch discussion starts around post 40 in that thread (this is a clickable link):
Also the following FAQ might be of interest: