Netgear DOCSIS 3.1 (CM2000) Nighthawk Multi-Gig 2.5Gbps Cable Modem $180, CM1200 $162, CM1000 $144 plus Free Shipping (Xfinity compatible modem) $180 at Netgear

Netgear is having a Flash Sale.

You will see a pop-up for a 10% coupon to sign-up for email promotions. After signing up, you will get a coupon code in your email in about 10 minutes, which works on top of the sale price.

DOCSIS 3.1 Cable Modem (CM2000)
Nighthawk® Multi-Gig 2.5Gbps Cable Modem
The Nighthawk® 2.5Gbps Internet Speed Cable Modem uses next-generation DOCSIS® 3.1 technology to deliver the world's fastest cable internet and prepare you for all future upgrades from your service provider.
https://www.netgear.com/home/wifi/modems/cm2000/
Retail $249.99, Flash Sale $199.99, after 10% coupon $179.99 (compared to Amazon's lowest price ever $199)

DOCSIS® 3.1 Cable Modem (CM1200)
Nighthawk® Multi-Gig 10Gbps Cable Modem
Stop renting and start owning. This Multi-Gig Speed DOCSIS® 3.1 Cable Modem supports link aggregation to deliver true Multi-Gig Internet speeds. Works with all major internet service providers for a seamless connected experience.
https://www.netgear.com/home/wifi/modems/cm1200/
Retail $229.99, Flash Sale $179.99, after 10% coupon $161.99

DOCSIS® 3.1 Cable Modem (CM1000)
NETGEAR Gigabit Speed Cable Modem
Get the fastest internet speeds of today and tomorrow with a DOCSIS 3.1 cable modem.
https://www.netgear.com/home/wifi/modems/cm1000/
Retail $189.99, Flash Sale $159.99, after 10% coupon $144

Includes free 2-day shipping.

I needed to upgrade the cable modem after taking advantage of the SD for the Xfinity 400Mbps speed tier.

Check mydeviceinfo.xfinity.com [xfinity.com] to make sure the modem is approved and compatible for your internet speed tier.

For me the CM2000 was listed as compatible, and plenty of future proofing (if not overkill)