I've been researching this myself as I'm thinking of installing one. There are many brands available. Companies that make electrical panels often make these, eg. Cutler-Hammer, Siemens, Federal Pioneer, Square D, etc. One place you can find them is at your local Home Depot around the area where they stock electrical panels. Or they might be locked up at the front of the store near the cashiers with the circuit breakers. There's also usually some brochures on the models they have with some information about the level of protection. If you're handy and comfortable with electrical circuits, you can install it yourself, at least if it's one that's installed on the electrical panel, as opposed to one that's installed before the electrical panel. That would be a pro installation unless you're an electrician. The level of protection is typically a little bit better than a good quality surge supressor that you would put behind your equipment rack. The manufacturers often recommend that you have two levels of protection. Install the whole house surge supressor at the panel as the first level of protection, and then have a local surge supressor with whatever equipment you want to specifically provide a second level of protection to, like your stereo or computer. The whole house unit has the advantage of protecting a lot of electronics that you wouldn't normally buy a stand alone surge supressor for, like for the electrionic chips that might be in a refrigerator or microwave for example. The price seems to be about $300-$700, depending on the particular model. Different models have different levels of protection. The following link takes you to the page of one of the manufacturers. A Google search should easily find others. I'm familiar with installations at the panel, but not with ones that you might put before the panel.
http://www.eaton.com/EatonCom/Markets/Electrical/Products/ResidentialProducts/SurgeProtection/PrimaryProtectionServiceEntrance/index.htm?ssSourceNodeId=3693&ssSourceSiteId=EatonCom
http://www.eaton.com/EatonCom/Markets/Electrical/Products/ResidentialProducts/SurgeProtection/PrimaryProtectionServiceEntrance/index.htm?ssSourceNodeId=3693&ssSourceSiteId=EatonCom