Culturing tubifex worms are bit more tricky and costly than you expected. Farmers must spend extra time feeding and monitoring the culture to get the maximum harvest. So that is why tubifex worms are expensive in the market. Even if the seller finds them in a natural live location, the seller needs to put extra effort, time, and cost to clean Tubifex properly. Those are the reason tubifex worms keep expensive in the aqua market.