Take a look at Richard Schmid
"ALLA PRIMA, Everything I Know About Painting".
In this book he divulges his palette and suggests a series of color charts based on it. His palette might not be for everybody, but it is complete, economical (with exception of the yellows), and most importantly, permanent. The charts are lengthy and require commitment to see through. I did them this summer and they were my introduction to oils.
If not for the charts - as it seems you have been exploring your own mixes - at least you should investigate his palette. He arrived at it the hard way and has been gracious enough to share that knowledge.
While you don't have the book, take a look at his FAQ page, where he explains his palette and choice of manufacturers:
http://www.richardschmid.com/faq.html
Greetings.