How do you evaluate "tf2/csgo keys price" for games you offer?

From my own experience trading you will be extremely unlikely to get 1 TF2 key for a single game from a $1 humble bundle. If people are trading TF2 keys for very cheap bundle games then they will generally be wanting multiple games.

Treat a key as roughly worth $2/€2. In your example it's really unlikely that anyone would pay a key for a single game at $1 tier, but maybe more likely for all the games at that tier. Same logic for other tiers.

I got a 4 pack for 2 keys, it was glitched in some or all of the South East Asian countries after they introduced regional pricing but before everything was region locked if I'm remembering it corrercty.

Edit: Looking further into it, it was in November in the Indonesian store.
Re-edit: Price was 36, 599 Indonesia Rupiah for the 4 pack which is around $3 US.

No but I wish I was, I always could some extra cash ;^)

The post wasn't all that serious and elaborated to begin with but here are some thoughts:

• marketPrice(key) would be the price of a chest key in the "market". This market refers to the trade that goes on outside the Steam controlled platform, and this includes RMT, keys to metal, etc.
• communityMarketPrice would be the price on the Steam Community Market, often equal to buying from Valve directly.
• "nKeys will be higher the lower market prices are": yes, that would be the point, because the lower the price the keys go for the more keys you will want for your game or item.
• "Dividing what you paid with the market": it woud be what you paid times 1.5 and by the lowest price the keys go for. It makes sense when you want to get the most keys in exchange for your game or item.
  Reminder that was supposed to be about the "happy merchant" way, that is for profit and/or stability.
  Maybe I am having a mental fart and it really doesn't make sense. Feel free to let me know.

in other words your variable 'k' is unknown

It's known - it depends on key price, not app :)

Yes, the Steam Community market. The point is that you should get at least the amount of Steam Wallet that you paid for the game.

For example, say you bought a game for 14.99. The current price of TF2 keys on the market is basically 2.49, which means if you sold your keys you'd get 85%, or 2.11 (rounded down). 14.99/2.11 = 7.104 keys, so you'd just sell for 8 keys, or bargain to a minimum of 7 keys and .104 x (current price = 19.11) = 2 ref.

EDIT: Keep in mind this is a calculation for the minimum you need to break even - obviously if you're ever looking to profit you should charge higher than this. Doing the same calculation when you want to buy games (with keys) will help you decide whether or not to just sell them all on the market and buy the game with steambux.