In the Hexyz Force universe, there are no shops to buy or sell items. To sell things in the game is to extract them for FP. To get items, is by locating treasure chests, Force scanning the area, and by Fusing items.
Fusion (合成・生成?) is where you personally synthesize material items dropped by monsters or harvested from points. NOTE: that the items from harvest points can be regenerated after around 5 battles, with a slim chance of rare items.