I made a small chart for myself a while ago, while Blade and Soul was still alive, for the credit cost of buying bronze cards from the shop and the total costs of each card in each prerequisite;
1 iron = 3 lead
1 bronze = 3 iron or 9 lead(17,500)
1 silver = 4 bronze, 9 iron, or 36 lead(70,000)
1 gold = 4 silver, 16 bronze, 48 iron, or 144 lead(280,000)
1 cobalt = 6 gold, 24 silver, 96 bronze, 288 iron, or 864 lead(1,680,000)
If you got all lead cards from 1,000 credit store cases, it would cost you 888,000 credits to craft up 1 cobalt, which, according to the mathematics in this thread, is a net increase of 495,334 credits(over a 1.5x increase), including the 50,000 fee for actually making the card, an increase from 24,000 and the added fragment cost.
The servers crashing at the end of the game and forfeiting all of your XP and earned credits, not to mention mission progress, makes it pretty hard to accumulate enough even then at the moment.
I traded 5 gold cards and 4 cobalt cards and got a grand total of 31,000 shards; cobalts cost 20,000 shards to make and give back 13,000, and golds cost 2,500 and give back 2,150 shards. This means I lost 28,350 shards worth of card value and would then have to spend another 50,000 credits on top of that to make a single 1/18 loadout/skin chance cobalt card. They also said that it would be cheaper, but it’s only cheaper from bronze -> silver -> gold, everything else is inflated out the wazoo.
I could have made 3 cobalt cards with all that, now I can only afford one.

