Congrats on finding the leak. I don't think you should be buying new tube every time one goes flat, just patch them. I've had tubes with as many as 15 or 16 patches, and you can do that as long as one patch doesn't overlap another or its very near to the valve...which I have patched those before but it's not recommended.
Also if your trying to use your bike to commute or just plain tired of flats then do as Wildbill suggested and get the Specialize Armadillo, they are the most flat resistent tire on the market. I use to live where the Goatheads roamed and the thistles and thorns played, and averaged 4 flats a week! I was trying to commute to work as well as excercise training and was getting very frustrated, then an LBS told me to try the Armadillos...14,000 miles later and only 2 flats, one was due to a faulty tube and the other because I had wore the tire down to the cords and a pebble made it's way through. The tires are heavy but no flats equals no boss yelling at you because your late-AGAIN. I do use Specialize 65grm racing tubes in the Armadillo in a attempt to keep the weight down.
There is a tire on the market called the Conti 4 Seasons, it's lighter by about 125grms then the Armadillo, it has the best flat protection for it's weight class, and they even extended one of the three anti-flat belts into the sidewall, no other company does that except for the Armadillo.