I wanted to start a thread expanding on a separate forum question about if someone should build a CoA or buy one. There are quite a few legendaries where buying is a better option to building (unless you just happen to have excess of the components to make them on hand). I thought it would be helpful for some players to see where the inflection points are in that market.
For the most part, the trade good costs to build every legendary are similar except for 2019 legendaries (extra Golden Fleece) and CoA. They all require $25K gold plus a wish ring or another $10K gold. Laz/Chad has the best prices normally for gold at $15/1K. That works out to $525 in gold costs. Add 1 GF, 1+ Argonite, 4 (in combination) of Oil/Bismuth and you have $150 in Trade 2+ materials. Assume you get everything else really inexpensively at $2/bit for the remaining trade goods - let say an average of 70 bits per transmute at $2 each = ~$140. So far, you are in $800+ (some Trade 1 you can get for under $2 but average that against items requiring more than a total combined of 6 of Trade 2+ and $800 is pretty conservative).
The next step is the cost of the ultra-rares and 4 point relics to get to the final transmute. Assume no 4 point costing more than $300 (likely too low but a good starting point), your minimum cost before the last components is already $1,050. Then you add UR's - many of which are out of print. Quickly buying a legendary is a better option than building (except that building can be done in steps as opposed to all at once spreading the costs out over time - ultimately if you just set the cash aside you'd be better off in the same situation).
CoA is a little different in the math.
Secondary market cost for a Ring of the Riches ($500) (3 points) and 2 CoGF ($325 each) (2 points each) works out to $1150. That seems to be the lowest cost to get the URs that I can find. That is before the other component costs - add 10K in gold at $15/1K (Laz/Chad has the best rates generally) = $150 plus 1 argonite, 1 golden fleece, 4 elven bismuth, 2 oil of enchantment, and 4 alchemist parchments (the other tokens at various times you can get for $1 or $2 each) - if you get good deals, you can get this group for around $175-$200. Add another $20 for the other trade good tokens (if you get them cheap) and you can build a CoA for around $1,500.
It isn't close - you are better off buying a CoA than making one. If the legendary cost is below $1,200 - this is true of some other legendaries with out of print URs involved (remember, the baseline cost for trade goods and gold for any will be $800+ before URs/4 point relic.)
Legendaries that are in demand that are cheaper to buy than make:
Aron's Robe - cost is around $1,200 to make, secondary market around $1,100
Asher's - cost is around $1,500 to make, secondary market around $1,200
CoA - Cost is around $1,500 to make, secondary market is around $1,100
Drake's - Cost is around $1,300 to make, secondary market is around $1,100
Drue's Baton - cost is around $1,500 to make, secondary market around $1,100
Giln's - cost is around $1,300 to make, secondary market is around $1,200
Io's Bow - cost is around $1,400 (mainly due to the sling cost), secondary market is around $1,300
Pern's - cost around $1,400, secondary market is around $1,200
Roland's - cost is around $1,200 to make, secondary market is around $1,300
Legendaries roughly equal to build or buy
Averon's Deathcleaver - normally sells for $1,500 - you can build one for around the same
Giln's - normally sells for $1,200 - costs around
Relsa's - $1,200 roughly either way
Cheaper to build yourself:
Pharacus's Cloak - normally sells for $1,200-$1,300 - costs around $1,100 to make
There are also legendaries that are a bit of date or just not as appealing that can be bought well below their cost to make:
Khing's Ring of Supreme Evasion (I hope this is used in a transmute one day to give the people who made one a sense that it was worth it) - typically available for $700-$800
TaMor's +4 Bracers - available for $500, would cost
Byr's/Sil's Plate/Mail - typically available for $1,000, would cost $1,200+ to make
Welfor's - typically available for $1,000 or less (this makes sense because it is class limited and, arguably, not as good as Thor's hammer)
Anything new will, generally be at parity (same cost to build/buy) because you can get components via PYPs for around $110 each and the 4 point for around $250. As these go out of print, they will likely get to be more expensive to build than buy because of increasing costs in OOP URs and higher trade good component costs.
Overall - the best deals in buying versus building are CoA ($400 savings), Drue's ($400 savings), and the armors (about $200+ savings). Of course some are amazingly less expensive but not as useful (bracers, etc.).
Fred