Similar to my above looks, here is some data for the NA Nintendo Gamecube library. For this calc, i considered loose, CIB, and New games.
Assumptions:No hardware (i.e. consoles, controllers), no unreleased games, no homebrew, no Player's Choice versions, no collector's editions, no variants. Total number of NA games for this calc was determined to be 560 using the above assumptions. Looking online I have seen a complete library numbers exceeding 650ish, but I'm assuming those include variants/player's choices of which I removed.
Note: According to Pricecharting, there are no recorded sales of loose disc "Sonic Adventure 2 Pack" and as such, only 559 games were used for loose disc calcs. However, this is the 2nd most expensive game (for both CIB and new) and would most likely be priced in the $500-$1000 range for a loose copy.
Calculations/methods:Same as for my NES report plus a few comparisons
Results:Using the above assumptions, the associated costs for a complete North American Gamecube collection are as follows:

The estimated cost of a loose Gamecube collection is approximately $38,000 less than a loose NES collection (which costs ~$49,000 for a collection that includes Stadium Events) or $18,000 less for one that doesn't include it. A CIB Gamecube collection costs about $9,000 more than a loose Gamecube collection and a new collection costs about $44,000 more than a loose collection.

Pokemon Box is the most expensive GCN game for all three tracked conditions while the cheapest game varies for each. In each respective condition, Pokemon Box costs as much as the sum of the cheapest 178 (loose), 170 (CIB), and 166 (New) games. With respect to each condition, it holds approximately 8.3%, 7.1%, and 7.9% of the complete collections value.
Discussion:There are approximately 444 loose, 365 CIB, and 59 new GCN games that can be had for under $25, with 348, 230, and 3 of those costing under $15. There are 15, 35, and 128 games which cost over $100, with 4, 8, and 45 of those costing over $250. 1, 2, and 2 games cost more than $1,000.
Conclusion:Prior to this activity, I knew nothing of GCN collecting or the associated costs. I assumed it would be high like all retro gaming nowadays but i didn't know where it would rank amongst other consoles. It was previously suggested that GCN costs were incredibly high so I thought it would be interesting to take a look. While the costs for a NEW GCN collection are currently greater than $50,000, the cost for a CIB collection (just over $22,000) is about half of what a CIB NA PS1 collection was previously determined to be (~$40,000). Of course, there are 560 GCN games to around 1300 PS1 games so a total cost comparison is not exactly an apple to apple study. In order to get a more accurate comparison, it would be better to understand the average costs. When viewed as such, average CIB costs are approximately $39 (GCN) to just under $31 (PSX). This makes CIB GCN collecting about 25% more expensive per game than PS1 collecting. This is interesting as the PS1 is an older console and considered to be a 5th generation console while the GCN belongs to the 6th generation (which includes the PS2).This might be explainable due to the "Nintendo Tax," individual game rarity, or even an abundance of "shovelware" titles on the PS1 which help to drag overall costs down. A more detailed look at the two consoles with additional filtering out of "shovelware" games from both console libraries might provide for more meaningful analysis, but was not considered in this calc.