Wireless router advice.

Hello everyone.
I'm looking to buy a wireless router in order to wifi-up a small appartment.
The problem is i use wired connections at home and don't know anything about wireless routers, which brands are good and if it even helps having 2 antennae instead of one.
The appartment in question has 3 rooms separated by concrete walls with steel reinforcements, so I'd assume that not any router will do.
I'll welcome any advice partaining to Brands/models or anything that might help.
Budget-$30

Thanks in advance!