The shaders actually do this really cool flashy thing as you move them from the shopkeeper to your inventory. Don't trust my word, find out for yourself! Its nuts! Such a cool effect... I'll be home later tonight to refill the inventory so more people can witness the spectacle.
Are you looking for HyperStims? Check the shopkeeper right next to the Medusa Teleporter (Medusa Baazar Mall). The shopkeeper is 1 meter away from the TP, and stocked frequently.