In addition to everything has already been said above.
It’s even easier to buy Radiant Khada Crystal from Auction. Yes, this is a rare thing, but there are much more of them than it is necessary for upgrade, so the price is literally symbolic 10-20 ped.
It is even cheaper to buy ready-made Improved A105 (at current prices) than to improve it yourself. You will save a couple hundred ped (and efforts).