Prices have steadily risen since my last look at the end of December. From December 29 to Jan 29th the average cost of crafting a legendary has risen by 170 gold, or just over 5.5 gold per day.
Breaking down legendary weapons by type, I was surprised to find that the ranged weapons (Dreamer, Kudzu, and Predator) have risen in cost faster than the other legendaries, averaging a 240g increase over the past month. Visually, here is the rise in cost of each legendary weapon, excluding vendor materials:
Breaking down legendary weapons by their components, its still clear that - for most legendaries - the precursor is the predominant cost.
This is particularly unfortunate, given news that the precursor scavenger hunt would not be in the Jan/Feb/March update.Looking across all legendary items, the relatively steady prices across the end of December were driven by a decline in the cost of most components offsetting a rise in the cost of Globs of Ectoplasm. Since then, while the price of globs has fallen, the cost of all other components has steadily risen, leading to an overall surge in prices each week.
Happy hunting!
If you have any other questions, leave a note in the comments / send an email, I'll see what I can find.