Every time I have ordered from Nature's Flavors, I ask in the comments of the order to have my order shipped USPS flat rate shipping. This is what I was told to do by NF over 2 years ago when I emailed them about the high shipping cost for such a small amount. It used to be $5.99 for flat rate from them, but I think the last time I ordered it was $7.99.
I'm waiting to see what ecx gets and how much they charge, but if you find a flavor you love, you can't beat NF's price for 4oz bottles if they'll still ship USPS.