All kind of watercolor art supplies are superbly represented by the dick.com website.
You can have a lot of choice: Blick owns colors, Da Vinci, Blocks, Daler-Rowney, Grumbacher, Holbein, Graham, Maimeri, Old Holland, Pebeo, Rembrandt, Schmincke, Sennelier, ShinHan and of course Winsor & Newton (probably the most used and/or respected single brand by watercolorists worldwide...).
However, I give you a great a tip and suggest to buy these Russian colors sold by an European (Germany, Switzerland, Austria, Sweden...) very reliable art supply online store:
Igor Trestoi, excellent quality/price ratio!
And here a wetcanvas review with a comparison with Winsor and Newton watercolors versus Igor Trestoi.
Igor Trestoi Colors (in German) Kadmiumgelb zitron, Kadmiumgelb mittel, Goldgelb, Kadmiumorange, Ockerrot, Eisenoxid hell, Scharlachrot, Krapplack hellrot, Karmin, Ultramarin, Kobaltblau, Sepia, Hellblau, Rotviolett, Smaragdgrün, Gelbgrün, Grün, Umbra, Umbra natur, Umbra gebrannt, Siena natur, Siena gebrannt, Ocker hell sowie Neutralschwarz.
in English (my translation): Cadmium Yellow Lemon, Cadium Yellow Medium, Gold Yellow, Cadium Orange, Ochre Red, Ironoxide light, Red Scarlet, Kraplack Light red, Carmin, Ultramarine, Blue Cobalt, Sepia, Light Blue, Red Violett, Smerald Green, Yellow Green, Green, Umber, Umber Natural, Burnt Umber, Sienna Natur, Burnt Sienna, Light Ochre, and Neutral Black.
Oh, the price is about 35$ (USD) for 24 colors (they come in a carton-box and you need to have a metallic bocx to keep them. The size is a full (not a half) size,
Whereas this is my comparison of the Igor Trestoi versus the Schmincke student edition (Akademie) and four Van Gogh colors...
Below a large picture of the Igor Trestoi 24 colors...
I was trying to understand if the colors were Transparent, Opaque and Stainer, a very important part in understanding watercolors and which you can learn about for instance in Sue Archers DVD.
Pigment carachteristic chart (from The Watercolorist's Essential Notebook - Landscapes but another useful book with similar content is Watercolor Artist's Guide to Exceptional Color) : in watercolor is very important to know if a color is Transparent, Opaque , a Stainer or Granulating (for a nice texture effect like grainy patches). For instances Sue Archer divides her colors in these categories:
Transparent (for light values):
Granulating: (for mid-values)
Stainers (for darks)
Opaque (she used them always lightly greydown using the Quiller Color Wheel)
Then she start working from light to darks going through different areas. She also prepares in advance her grays which she keeps in water in small containers and then put she keep them in the fridge.
How to mount a watercolor painting on board