Don't forget that when you make the Exotech Stims, you get a stack of 3. So even with crafting costs at the high end of 20k, that's a profit of almost 100% if sold at 13k each, and just over 33% if sold at 9k each.
No, I've already considered this. They cost 48-60k to make. Of course nobody buys the radioactive pastes at 9k each (or nobody should because they sure wouldn't have any profit that way..), but you have to consider the prices for them at the market, why craft something if you could instead sell the mats for more?