I wear Turnbull & Asser shirts for business but for business casual it's tough to beat Polo Ralph Lauren. The price is sensible and those clothes last very well. The only brand of casual shirts I buy myself anymore.
There are a lot of ...... stores where you can pick up Polo shirts silly cheap. I only buy business clothes in the UK now. For all my casuals, I buy when I'm in the US when the price versus quality are in my favour.