Ant's Many ants have appeared recently how to get rid of them CHEAPLY?

I have today encountered many ants but before today there was only about the occasional one or two I would find. No my house isn't a mess no food left out garbage of food scraps are removed before the meal is over. The Ants I am finding are small not like the ones I see outside. Would this be an ant that might be living in the walls... ALSO THE HOUSE I HAVE WAS A FORE-CLOSER I HAVE ONLY LIVED IN IT FOR 2 YEARS. Just to let you know.