I'm a master seller in ESO. I've never bought the recipe because it hasn't looked worth the effort to me to be a mythical ambrosia seller. Here's how I look at it. These are PS4 NA prices...you might double check your guild stores to see if your platform is different.

The recipe can net $2 million.
Mythical ambrosia will net $30k per pot
Dust costs $90k
Standard psijic is worth $4k

Therefore, if you become a seller let's look at the profit model. A mythic costs 1 psijic. This could sell for $4k, so we build that into the cost of a mythic. That psijic plus a $90k dust makes four. So our per-potion cost is 94,000 / 4 = 23,500.

If you're selling these for 30k, that's $6,500 profit per pot. You need to sell 305 to break even on the money you would have made just selling the recipe.

In my guild stores, $30k mythics have been around for 7-15 days. That tells me they don't sell that fast. Some stores have people dropping the price to $28k...it'd take thousands of sales for that price to make sense.

There are easier ways to make cash...my assessment is that selling the recipe makes the most sense.