I use Winton oil paint that I get for £8 for a 200ml tube (for any colour). Some tubes from other ranges (from the same shop) cost up to £160 for a tube the same size - and there is different pricing for different colours. There are several different ranges in between at different prices.
Why the huge disparity in pricing for paint, and what do you get in the more expensive ranges that you don't in the cheap stuff?
There are many things that can set apart great paints from others:
Each of these can mean different things to the rest of the materials you will use in producing your painting, which is a bit beyond the scope of this question.
On one hand there is the general quality of the paint such as the formulation of the base, density and particle size of the pigment as well as the consistency of quality from one batch to the next.
There is also the pigment itself. Traditional pigments can vary hugely in price depending on the source and although there are inexpensive synthetic equivalents of any colour you might want specific pigments may be desirable for more subtle and specific qualities of transparency and luminosity. One example is real ultramarine which is made from ground lapis lazuli and is very expensive indeed, the dry pigment powder almost seems to glow in daylight.
More traditional pigments may also be desirable for reasons or historical authenticity or for reproducing specific techniques and effects. A lot of mineral pigments are metal oxides and may be toxic and so tend to be much more expensive to process and get hold of in the context of modern consumer safety regulations.
In practice this often comes down to how the pigment itself reflects light. Many oil painting techniques rely on building up many semi-transparent layers to achieve sophisticated lighting effects, especially for things like skin tones and atmospheric effects which you obviously can't do if the paint has a lot of opaque filler.
Always buy the best you can afford.
The answer can get complicated, but generally the lower priced brand use only cheap manufactured pigments and fill the tubes with cheapo filler, over diluting them . The same is true for "student grade" version of good enough brands like W & N.
Almost always the cheaper paints are actually more expensive than quality paints, in view of the amount of actual pigments used.
More expensive brands have a broader palette because they use some pigments that are more expensive to produce and some natural pigments that are more costly to acquire.
