Does Apple make a modem?
Apple don't make a modem, but depending on your internet/cable/fiber provider, you may be able to encourage them to give you one for free. 

I have Virgin Media in the UK and new customers receive a new Super Hub free (which can easily be configured to be a slave modem, you just turn the wireless off). The same is true of most of the free 'hubs' provided by networks these days.