You're new to the oil painting scene but you have to start somewhere. Here is a breakdown of what you're looking at.
Presupposition: You are shopping at a fairly regular art store- not fancy and not a basic craft store.
Cheapest
In the cheap section you are going to find brands like:
Van Gogh
or the store brand ( at Hobby Lobby it's called "Master Touch")
Gamblin 1980
Winsor & Newton's Winton Colors
are both in the cheap section but they are much higher quality than Van Gogh or a store brand. They essentially a student line vs the fancy artist line. But since they come from good brands they are still rich with pigment.
If you know you are going to waste a ton of paint just learning how to use oil paint then getting the cheapest thing might be best for you. However, if you can affordable Gamblin 1980 or Winton, go for it. You don't want to waste time thinking that you are terrible at mixing colors if the real problem is the quality of your paint.
Affordable but Good
Winsor & Newton
Gamblin
These brands make excellent paints and they are what I use 99% of the time. Sometimes I'll buy a Gamblin 1980 or I'll splurge on a single color of a more expensive brand. But for the most part Gamblin is my sweet spot.
What I also love about Gamblin - they have a very comprehensive website that provides tips and instructions on how to use all their products.
Expensive
Brands you'll find in this section:
Holbein
Old Holland
Michael Harding
Rembrandt
Sennelier
Williamsburg
These paints are professional grade. If you are ready for them you probably have already been painting for awhile. I wouldn't jump into these unless you have experience under your belt.
Also think about what you'll use the paint for. If you're using a burnt umber as a base that's going to be covered in several layers- save yourself the money and use a cheaper paint.
Check the tube. Paint is priced by "series"
The higher the series the higher the price.
Happy shopping!
-Amy