If you worry to get 9 APIS Drone, the cheapest way to get is collecting green pirates chest until 21 pieces, then buy with uridium rest of blueprints.
When you have :
21 blueprints you spend 192.500 uri
24 blueprints 170.000 uri
Well, after 21 everyone can see how goes ratio.
Average for blueprints parts are 3/50 green pirates chest.
After you have APIS, blueprints parts not count until next drone, probably.
My opinion about ratio on lf4, till now: average 1LF4/250.000 uri
But is not a fact, not relevant sense you have to find a lot of LF4 to make a average ratio.
When you have :
21 blueprints you spend 192.500 uri
24 blueprints 170.000 uri
Well, after 21 everyone can see how goes ratio.
Average for blueprints parts are 3/50 green pirates chest.
After you have APIS, blueprints parts not count until next drone, probably.
My opinion about ratio on lf4, till now: average 1LF4/250.000 uri
But is not a fact, not relevant sense you have to find a lot of LF4 to make a average ratio.