Help! Pesky Gnats in the House!

Ugh, ways to rid house (well, bathroom and kitchen) of gnats. I tried bleach down the drains, I cleaned out the garbage cans themselves, dishes are being washed daily, I'm making sure there's no standing water. We don't have indoor plants. But nothing is working!
Today my poor little boy kept swatting at the gnats as they buzzed around him. 
Ideas? Besides calling an exterminator. Calling for an exterminator is my last resort as I don't have much disposable income.