Bob Ross® Bright Red Oil Paint
Bob Ross® Bright Red oil paint is one that will be used in small amounts, but frequently. It is used most often to mix various shades of highlights for trees and grass. In painting fall scenes you'll actually use quite a lot of Bright Red in creating highlights. Most importantly, you can use Bright Red to sign your painting. 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® Bright Red then you might consider buying from a reputable, high-volume art supply dealer online. The normal list price for the 5 OZ tube of Bright Red 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.