The Motorola MB8600 has been out of stock since April.
The SURFboard SB8200 is hard to find.
Almost every Costco seems to have the CM1100 in stock 🙂
For the record... I've had mine now for a few months and it has been ROCK SOLID.
As mentioned above, you will still need some type of 'firewall/router' to protect your network. Most people use their WiFi router for that. Your other option is 'build your own' with something like PFSense (which gives you way more control over your network.. IMHO).