What it actually costs to transmute a mythic item is going to be a large discussion item. Thankfully there is more time to refine the cost than there is to actually design the tokens, but that doesn't mean the cost should be ignored.
The guidance from Jeff is:
Jeff Martin wrote: ...they should cost about 50% more than a 2025 Legendary due to the big cost to make a Safehold I token. Let’s make the recipes the exact same for all Mythic tokens (except the Coin of Wealth).
The recipes for the Mythic tokens should be much like other Transmute tokens – using the standard Trade tokens. The only new thing I want to introduce to the whole Trade program is a 100,000 GP Bar that will be used in all Mythic token recipes.
The Coin of Wealth will likely be the only thing some Safehold I owners will make. That token should probably cost more than the other Mythics…maybe 2-3 times a 2025 Legendary.
We should design ALL Mythic tokens this year, and promise not to make any new ones in the future. That way folks can make informed decisions about what to make, and they don’t have to worry about new cooler Mythic tokens showing up later. The recipes will be fixed, too.
First I want to note that the guidance is somewhat conflicted. Gold + Wish ring (or extra 15k gold) is generally one of the most expensive portions of a legendary transmute - about 25% of the Sunstone is gold based. If a mythic is going to require a 100k bar, the gold cost alone of a mythic will be the cost of an entire 2025 legendary. For the spirit of the conversation going forward, I'm going to assume that Jeff really meant that Silk, Plank, AG, EB, etc should be 50% of a 2025 legendary. I'm also going to go on a limb and guess that Golden Fleece should not be reduced.
Personally, I think that Mythic items should include a legendary in the transmute cost, and should have a branch between using a legendary transmuter that came with SH1, or a more expensive option. This allows a player that made a SH1 to make up to 5 Mythic items, but they aren't gated at having to make and sell a second SH1 to build additional mythics. I suspect that building SH1s just for the mythic transmuters would have some undesirable impacts on how SH1s are built and sold in the future.
Let's pretend that we're making a mythic belt called Runewrap that grants +11 Strength. I'm thinking the recipe should look something like this?
Surtr’s Girdle of Fire Giant Strength
10× Alchemist’s Ink
10× Alchemist’s Parchment
1× Aragonite
10× Darkwood Plank
10× Dwarven Steel
3× Elven Bismuth
1× Enchanter’s Munition
5× Golden Fleece
5× Minotaur Hide
10× Mystic Silk
3× Oil of Enchantment
15× Philosopher’s Stone
100,000 GP Unobtanium Bar
plus ONLY ONE of the following:
Mythic Transmuter
OR
Any Legendary