Bob Ross® Cadmium Yellow Oil Paint
Bob Ross® Cadmium Yellow oil paint is a color that you're going to use a lot of. It is mixed to make everything from beautiful glowing skies to brilliant highlights on trees and grass. If you paint often, the 5 oz tube will be the way to go, otherwise, the 1.25 oz tube should last you quite a while.
If you cannot find a local retail outlet for Bob Ross® Cadmium Yellow then you might consider buying from a reputable, high-volume art supply dealer online. The normal list price for the 5 OZ tube of Cadmium Yellow is $17.49 and the 1.25 OZ is listed for $7.29 but you can buy it online for far less. The buy link below doesn't commit you to buying but will take you to the merchant website where you can see what is available.