You do not need a big box of colours to start oil painting. The course uses four tubes: titanium white, yellow ochre, a cadmium red and ultramarine (sample list).
Add two hog-hair brushes, a filbert and a flat, a palette knife and cotton rags. We provide odourless solvent in the studio and dispose of it safely.
Buy student-grade paint for now. Spend money on better paint once you know which colours you use most.