Hugs to you hun and what a lovely bug sis you are
If you are willing to spend some money an iPod touch would be an awesome gift, I also second smiggles , nice doona cover, etc.
May I also suggest (if you a worried that the pressy won't be given to her) set her up a bank account with you as a signatory and put some money in that for her future and then buy her a smaller gift.
Also if your still concerned for her welfare maybe contact DHS and reopen the case and maybe contact relationships Australia to arrange supervised visits, they used to utilize my work, the meeting would be arranged by them then one parent used to drop the child in at one entrance and the other parent would enter via another entrance so that the two parties never meet. Please don't quote me on this because I don't have extensive knowledge but I think you have some rights to access.