For fiber, I found a cheap one at Target that only had 1 more gram of carbs per serving than fiber, which is important for my low carb diet. That being said, just find a powder that will mix in a drink. That's the best kind to use.
Remember a huge part of paleo is veggies. People tend to confuse paleo with a low carb diet, which it isn't. It's lower in carbs than most modern diets just because it's grain free.
Any healthy diet, paleo or not, should include plenty of green veggies.
Current PRs at 242, raw w/ wraps- 525, 355, 605, 1485
Roboro tui, perimo vester adversarius
(Build yourself, destroy your enemy)