I work British custies in 6 areas, all squaddies, the rest are Germans. In 3 of these areas, I have 2 other WC's. I am the most expensive and have lost none to the other WC's even though in some cases, they are upto 20% cheaper than me. The longest squaddie custy that I have is 3 years, because they move every 2 or 3 years. So really, I am wide open to other WC's undercutting me.
I think it's not as easy as you imagine to build a biz by undercutting. In your head, maybe. But I get the impression that you aren't really a WC at all, and if you are, at best, a part time one.
Just my opinion.