Funimation has given us three ways to get the Code Geass Blu-rays.
Option #1 Season 1 a.k.a R1 or Season 2 a.k.a R2 separately.
Funimation released both editions in 2016. Unless you already have one of the seasons on Blu-ray it makes no sense to buy each one separately.
It will ultimately cost you more in the long run. Also, if you are curious all collections come with the same on-disc features.
So regardless of which option you choose just note that you are not missing anything.
You can purchase Code Geass Lelouch of the Rebellion R1 Blu-ray Here
You can purchase Code Geass Lelouch of the Rebellion R2 Blu-ray Here
Option #2 Code Geass Blu-ray Collection.
It might cost you more in the short run but it’s still cheaper than buying each season separately.
This collection comes in one Blu-ray case unlike the Collector’s Edition or the individual seasons.
The case is bare-bones and only for fans who just want to own the whole series.
Since this is going to meet most fan’s needs and is the cheapest option, I recommend this version the most.
You can purchase Code Geass: Lelouch of Rebellion – The Complete Series [Blu-ray] here
Option #3 is Code Geass Blu-ray Collector’s Edition.
This expensive collection is a box set that has:
1. Blu-ray cases for R1 and R2
2. 16 artcards featuring artwork from CLAMP
This collection originally was fairly affordable and a worthy buy during its initial release. But now the collection has spiked in price and is no longer worth it. Since the on-disc extras do not change, unless you really want the artcards this collection is not worth it.