I was taught to choose my finished art materials for the long-haul - lightfast pencils and a surface that will last decades, if not longer.
Finding acid-free, lightfast, durable paper & board is getting easier. I use Crescent or Strathmore Illustration Boards and Strathmore or Mi-Teints Paper (though lightfastness is an issue with certain dark Mi-Teints colours).
The pencil brands I choose are various, and all dependent upon lightfastness. I have Prismacolor, Derwent regular and Colorsoft, Lyra, Faber-Castell, and Caran d'Ache. I have some Rembrandt as a gift from a friend, which I use sparingly.
To pick the most lightfast colours, CPSA (Colored Pencil Society of America) has published a lightfastness workbook. CPSA has tested each professional-grade coloured pencil under rigorous scientific conditions in order to assure artwork that will last. This is an enormously helpful resource.
I've found that I can mix and match brands and types of coloured pencil in finished art without issue, albeit with practice. There's no real need to have a full set of any one brand if you can't afford one - just buy what you need when you can.
Hope this helped!