R.R.
I'd say if they ask what she'd like then suggest gift cards, otherwise then Yes, it would seem 'tacky' to request it ahead of time.
Why not pack up everything but the new toys she receives for the move? It may make the move a little more tolerable for her to have all of the new stuff to play with. Gift cards will be a nice shopping trip treat on the 'other side' to help her make the transition, but a few new favorite toys and games may help her through the first weeks. Besides, do you really want to hear 'When can we go shopping?' for the first few weeks of your move?