If I was looking for some solid color juggling bags on Amazon I'd check out the Zeekios. However, I've never used them so I can't vouch for them, but they look like reasonably good price and quality.
If you didn't want to spend much money, then I would suggest making your own from balloons. I use 12" party balloons filled with 130g of lentils. It takes 3 balloons per bag and all you need is scissors, a funnel, and a kitchen scale. They don't last forever but they are cheap, easy to make, exactly the colors you want, super grippy, and probably superior to the set you already own.