Just to add, if you insist on using RetroArch their folder hierarchy suggests the following:
/dev_hdd0/game/SSNE10000/USRDIR/cores/roms/vba for GBA roms
/dev_hdd0/game/SSNE10000/USRDIR/cores/sram/vba for srams (traditional console "checkpoint style" saving) and
/dev_hdd0/game/SSNE10000/USRDIR/cores/savestates/vba for RTS (real time saves.)
Hope this helps.