Router

[SanchoP]

.

 

[sn3rd]

They exist, but they're rare (and likely expensive). Much cheaper (and IMO, better) to just get a router + switch.

 

[PostmanPot]

1-port router + switch would be the cheapest option obviously, not sure though whether there are any advantages in doing it with a 4-port router instead, or any disadvantages in doing it with a 1-port router.

 

[Juggy]

You could always go for the Cisco 2821 modular router and put an ADSL and switch module in it.

This would set you back more than 30K which is probably a bit more than you bargained for