Grid Armor Nanos currently come in four different Quality Levels:
Grid Armor MKI
Grid Armor MKII
Grid Armor MKIII
Grid Armor MKIV
At this time, these nanos can only be found in Instruction Disc form as loot from a monster (MOB) or Non-Player Character (NPC) of approximately the same level as the instruction disc. The disc is then made into a nano crystal by another person (Player Character= PC) due to the extensive IP requirements it would take for a Fixer to do it himself/herself/itself.
They can be found in single player missions as regular loot, or from team missions as regular loot or dropped from the NPC/MOB in team missions that drops special items.
These discs can also be found in outside hunting areas from any MOBs of the appropriate quality level of the GA you wish to acquire. They also drop from the bosses of Dynacamps, again of the appropriate QL.
Grid Armor Instruction Discs and completed Nano Crystals can also be purchased from other players who have already found it. Purchasing GA from another player is usually extremely expensive due to the fact that it is a very rare item.
Grid Armor Instruction Discs are extremely rare. People have spent days or weeks searching for any of the versions and still not found it. Some people have found several. If you find one consider yourself very lucky. If you don't find one and can't afford to buy it, then simply continue with your character development according to your current pattern.
Good night and have a pleasant tomorrow.