<mark>This post has been edited by a moderator. Please refrain from soliciting or trading Microsoft Points or LIVE codes from other users.</mark>
It won’t be cheap since it’s rare and I wouldn’t recommend buying out unless the seller goes first.
The best place to find them is eBay but they are overpriced because eBay is one of the only places where you can get them brand new.
Halo: Reach came out like 6 years ago. The codes that came with the legendary edition are extremely over-priced or just don’t exist anymore. If you’re talking about the Eternal flames then they aren’t possible to get unless you played the game around 7/7/2011. The last Bungie day in Halo.