Small camera for Big Jobs?

I'm still holding off to shoot a commercial assignment with my Panasonic GH2. The reason is as simple as it is silly: appearance. Many clients still like -demand!- big camera's. And they distrust small camera's. I have heard people talk in derogatory terms about 'that small camera', 'that photocamera' and other nasty references to what people consider to be 'unprofessional equipment'. I have seen beautiful footage shot with the 5D Mark II, much more impressive than what I could do with my EX1R, but the one thing that stuck in their minds was that 'the guy worked with a really small camera...'. An ignorant remark perhaps, but it's the reality of working with certain clients.
I think a matte box will do an adequate job of impressing clients that require so... Well, in combination with the Gini rig, follow focus and an external monitor that I already have. But the matte box wouldn't just serve cosmetic purposes. I think the convenience of a matte box for adding and removing ND filters would be a great plus. A matte box is a simple system designed to hold filters and reduce flare. But looking at their prices you'd think you are buying high tech space constructions. Looking for a solid Chinese or Korean alternative but even the simplest design goes for well over 100 dollars. And that doesn't even include some rod-mount option. So if anyone knows of a quality, budget mattebox with rod-mount- I'm open to suggestions!