Hi Kim,
I can’t speak for other brands but when I started out in oils, I started using Winsor & Newton paint. I started using their ‘Winton Oil Paints’ range which are a cheaper version than their ‘Artists Oil Paints’.
As time went on I gradually started switching over to W&N Artists oils because you hear everyone say that students grade paints aren’t the same quality. But honestly I have found very little difference. I think they are both great quality. I have never had any problems with the cheaper version at all, and in fact some colors are not available in both ranges so I still use Winton Pthalo blue for example.
I have also added other brands here and there as time has gone on. I’ve become a great fan of Gamblin paints. But I also like Grumbacher Pre-tested Oils a lot which are absolutely gorgeous creamy paints.
Here’s a price comparison
French Ultramarine 37ml tube
W&N Winton $4.11
Grumbacher $7.10
W&N Artists oil $8.50
Gamblin $9.71
I think just carry on doing what you are doing, trying them out and decide for yourself. Keep us posted!