Okay! A couple thoughts: first, I think Bronley's estimate is a tad lower than mine.
Secondly, I was poking around, trying to think of how your shipping costs could be cut down a little. IF you're willing to sacrifice the Toys R Us fan favorites box for lower cost, I could take them out and send them in a large envelope. Assuming Nightmare Moon weighs ~the same as a molded Celestia, the ponies themselves would weigh slightly under one pound. First-class shipping for them would be $13-15. (If any didn't fit, any small package containing one PP size pony would be about $3.60, and fitting two extra ponies into a package would be about a dollar more.
I honestly can't estimate the shipping cost of Zecora-in-box because I don't know the dimensions or weight for her. :/
If you wanted it pre-ordered in case of TRU in-store stock failure, fan favorites + shipping to get to me would be $46.34. And then $10 for Zecora.
*deep breath* So at my highest estimate ($15 for shipping, though I actually think it would be less, but depends on Nightmare Moon), full cost of fan favorites would be approx. $64.50 (counting a little extra to compensate for Paypal's 2.9% + $.30 commission). Though probably under by a dollar or so, again depending on exact sizes and weights of ponies.