Would it be possible to set it up where buyers get the estimate for their shipping choice but don't pay anything up front for shipping. Then, after getting the actual shipping label and things put together, you send a separate invoice for shipping? If you explained it as, "I'm getting you the best deal I can for the shipping speed you want," I wouldn't have any complaints. Have disclaimers up front and all that too.
That's a good idea, but after having reviewed my options I think I'm going to do is create multiple regions (can be countries and provinces/states) where I define flat shipping rates based on weight. That way users can know immediately what their shipping costs will be and it will allow me to bundle accessories with cases to save on shipping. It'll take a while to define all the rules, but at least it will be a good average value so I can be as fair as possible. My only problem would ensuring I cap the weight for one order such that I don't have to define rules every 10-11lbs.
This being a low-volume enterprise, I have to be very careful not to lose too much money here because I set a value wrong. Yet I don't want to lose business either. Probably going to keep me awake at night thinking about it even after I set the values initially.
Alright, new shipping rates have been published. Good luck everybody!
Seriously though, feel free to contact me if you're having problems with the shipping or associated costs.
I also think I found a way to produce the panel spacers for around $15 a set. I'm going to order some more acrylic and see if my new design works.