Ok, there are a few things to discuss as what you are really are looking for. A lot of recommendations will be based on budget.
If you are just needing DATA redundancy and back up, it has already been suggested a NAS would probably suffice, unless you need to retain historical backups for years, then a LTO-5 for tape back ups will still be needed.
Now as for redundancy of the network itself. Routers for HSRP this will kind of depend on your connection type. Cisco 2901 in most cases will work if Ethernet is provided by your ISP or a T1 WIC.
If you have a DR site/COOP, then IPSec VPN across unless you have a dedicated T1 to the DR/COOP.
If your looking for redundancy for your core/distribution layers it will depend on the size of your network. Cisco 4503's (paired) or 3750X's paired would probably work. Obviously the 4503's chassis will give you greater port density than a 3750 series.
Regardless, if your needing to do a network build out and Back-up Recovery Assessment I would recommend getting a professional in to atleast evaluate what you currently have now and what you need also.
Make sure you have the Business Impact Assessment along with the IT Contingency Plan, so that individual can help make the best recommendations/practices for your environment.
Feel free to PM me if you need.