I don't pay tax + shipping by buying a box in a store after the realease. I play tax + shipping from stardock direct in order to get a beta key. 10 dollars in shipping = 22% of the 45 dollars for a DL copy, or what places like best buy and target will charge.
If you're preordering, even download-only, why would you then go to a store to get a box? Then you'd be paying double. If you want a box AND you want to get in the beta, what you did is the cheapest way. Any preorder direct from us gets you into the beta (we don't send out hard copies for the beta, only after release); preordering at retail would not.
More importantly, if you did not get in in time for beta 1, that means your order is actually queued and won't be charged until beta 2 begins (tentatively scheduled for next month). So if you want to change the order, it's as simple as contacting sales@stardock.com.