You need to go to a decent workshop to get your alignment done. Also when you get new tyres you should get a symmetric design so that you can have them flipped inside out on the wheels half way through their life to extend the use you can get out of them.

If you are killing tyres that quickly there is something wrong. I have -5 and -3 camber and I am still on the same set of tyres after more than 20,000kms. I got mine flipped inside out after 15,000kms or so.