We had used a company called Portagas until recently. They are owned by Praxair now. We get our CO calibration gas from them. Nice lightweight reusable aluminum bottles! They manufacture the calibration kits for people like GFG. They don't manufacture the 99% N2O anymore though.
We are currently using Airgas for N2O: P/N: NS UHPP34 (1.2 cu ft / 34L steel bottle)