You can go to the dealer ($$..been there with a few Jeeps) or get the generic packs like you are talking about. Check out a NAPA - they usually will sell you individual pieces and have a much better assortment to dig through.
The plastic hose is the same deal - just pick up a roll in the size you need. Otherwise you can usually replace sections with an appropriately sized rubber/silicone line instead. You can even use the rubber/silicone line as a splice on the existing plastic line if you don't feel like replacing (or can't easily get to) both ends of the plastic hose.