Dick Blick is my go-to online store for ordering supplies. They're reliable and always get the orders shipped quickly to my doorstep. Below are links to purchase materials if you need them.
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Saunders Waterford Sheet (the best)

Blick Premier Sheet - (affordable alternative)

Blick Watercolor Paper - (good for finished acrylic paintings and watercolor studies only)

Blick Spiral-bound Pad 9x12

Holbein Beginner Set (if you want to save money)

Isabey Red Sable Rigger (excellent for fine detail, thin lines, etc.)

Hake brush 1 1/2" (large)

Hake brush  5/8" (small)

Hake Brush 3” (extra large)

Plastic collapsible water pot 

Gator-board 16x23 inches (tape watercolor paper to for firm backing)

Gator-board 23x31 inches

Spray bottle/mister (purchase at target, Michael's)

Masking tape (Home Depot)

Large Sponge (Home Depot)