I just use boric acid and sugar on a cotton ball. I mix it in a 1:1 ratio and add water until it forms a paste and then put it in a cotton ball. It's good home remedy and the boric acid is just $2 at my local pharmacy. I also use it on my car (just sprinkle it on the rug) for cockaroaches and honestly I don't know where they go but they did disappear!
Also the best cheap remedy proven at least for the ants in Puerto Rico is just a bucket with water with a lot of the cheap dish soap that you can get for a dollar. Just mix until it has a lot of suds and pour it over the nest, depending they will either die or try and start fresh. If they do start again just repeat.
If nothing above works I just look for a 1" pipe stick in in the middle of the nest then remove it and on the hole stick some paper, then a lil fuel and enjoy the BBQ.