Mathematically, to get exactly 1 of the 9 possible cards, you would expect to have to craft 9 times, which is 13,500 credits and 1485 Fragments. To get one of the two you don’t have, you’d expect to have to craft 4.5 times (rounded to 5), which is 7,500 credits and 825 Fragments.
Add those two together, and you get an expected cost of getting the 2 cards you don’t have at 21,000 Credits and 2,310 Fragments.
Buying the 2 cards from the store would be 35,000 Credits.
If 2,310 Fragments are worth less than 14,000 Credits to you (~6 credits per fragment), Crafting is EXPECTED to be cheaper. RNGsus could still decide to hate you, and it could be that your cost is higher for crafting at the end. (It would take 24 crafts to have a greater credit cost, which you would expect to have 2 and 2/3s of each card.)
It is worth noting that the End-of-August Yet-to-Be-Named Crafting-Apology-Event-Thingy will reduce costs for crafting and increase fragments from recycling. If you wait til then (and the given 20% off isn’t changed), it’s and expected cost to craft of those 2 cards to ~1848 Fragments. There was no word in this post about credit cost reductions, but those would be nice. (I’d argue better than the fragment cost reduction.)