Better than a rental.
The TP-Link TC-7620 DOCSIS 3.0 Cable Modem is down to $34.99 on Amazon from a street price around $58. This cable modem rarely drops below $55, but it recently dropped to $45 and the coupon code 10762010D3 takes another $10 off the price. It's definitely the best deal we've seen.
We always recommend buying your modem and router instead of renting from your Internet Service Provider because the devices end up paying for themselves soon enough. You should also check with your ISP to make sure this router is compatible with your Internet. You'll need to pair this cable modem with a router, so we'd recommend a budget router like the TP-Link Archer C1750.
The cable modem has channel bonding of 16 downstream channels and four upstream channels. It can work with Internet plans up to 300 Mbps and comes with a two-year warranty. Users give it 4.2 stars based on 466 reviews.