Highly expensive or rare brushes are often found in the Auction House , which can sometimes be cheaper than the Trading Post if you win.
Here is a comprehensive guide to buying paint brushes in Neopets. Where to Buy Paint Brushes buy paint brushes neopets
During annual events like the Advent Calendar or plot rewards, special paint brushes are sometimes awarded. How to Get Paint Brushes (Without Buying) Highly expensive or rare brushes are often found
You can buy paint brushes through several methods, depending on your budget and which brush you are looking for. How to Get Paint Brushes (Without Buying) You
Jacko the Phantom Painter can randomly give you a paint brush. Tips for Buying Paint Brushes Fabulous Paint Brushes, and Where to Find Them - Neopets
For cheaper paint brushes (usually under 1,000,000 NP), the best place is the Shop Wizard . Use the Jellyneo Item Database to search for the specific brush to find the lowest price in user shops.
Using Nerkmids (38k–50k+ NP each) allows you to gamble for paint brushes, though you will likely get junk most of the time.