As a business owner myself, I can tell you that your email would most likely get deleted and not get a response. If I receive and email like that I usually ask the customer to please post on the forums as they are indicating. Whether you think you are bashing them or not, it's free links and advertising for them. A lot of viewers, such as myself, do not think any less of the company. I've never purchased anything from them before, but I've added them to my favorites.
There many customers who are purely shopping by price or free shipping. Those type of customers are catered to by fly-by-night vendors who undercut others and rarely stay around. Long term vendors tend to cater to customers who respect service, communication, AND a good price.
Shipping rates via UPS and FedEx go up at least once every year and profit margins rarely do. What you must realize is that you're paying for it somewhere. It's unlikely to ship a package for under $8-10 nowadays. We started offering, what we see to be a better promotion, a shipping discount. A discount percentage is applied to your shipping rates. This may mean you get free ground shipping, it may mean you get reduced ground shipping, or it may mean you can use your discount towards upgraded shipping.
I'd definitely recommend a different method when contacting vendors. The rude email will likely not amount to much.