You must own and be willing to redeem 3 copies of Space Trip to purchase G-Future. You may purchase as many open editions as you would like up to the amount of qualifying redemption pieces you own (i.e. 9 sent Space Trip grants 3 open edition purchases).
You must own and be willing to redeem 2 copies of G-KLA$$€ to purchase G-Vision. You may purchase as many open editions as you would like up to the amount of qualifying redemption pieces you own (i.e. 8 sent G-KLA$$€ grants 4 open edition purchases).
You must own and be willing to redeem 1 copy of each G-Construction piece in order to purchase G-Construction Extended.
The Lamp The Keys The Chair The Car
You may purchase as many open editions as you would like up to the amount of qualifying redemption pieces you own (i.e. 2 full sets sent grants 2 open edition purchases).
You can buy here:
https://www.niftygateway.com/marketplace/collection/0x1a4c685f6ebfaa429a11a58b96967a8fb7a5a4c4