You could buy from ztnetstore.com or jandaman.com, shipping is probably cheaper there as you live in the USA. But on the other hand, my Adaptoids are 5 dollars cheaper than both.
However, if you buy more than one Adaptoid, shipping is much cheaper from me (per item).
First item: $6
Each additional: $3.
One guy bought 3 Adaptoids from me the other day and only paid $4 each for S&H.