If you use http://www.dearelder.com it is FREE postage to both MTC's and Bolivia!
Bolivia:
Mission Bolivia Santa Cruz
Calle Saavedra esq, Cochabomba
Torres Cainco piso 7 of. 1 y 2
Casilla de correo 2042
Santa Cruz, Bolivia
phone. 333-7072, fax 333-7074