Heya,
The plano buckets can work as an easy way to carry a few baits. If I'm using smelt, I can carry about a dozen of them in one. They're pretty simple to use also: the low cost, no muss, no fuss system. If I'm going to paddle any distance, I bring it up on deck then paddle where I'm going, then drop it back down when fishing so the water can get changed out. Paddling with one in the water is like paddling with a drift chute in the water.
Powered bait tanks work well also. You can carry more bait with them, but they require a pump and battery setup. They work out pretty good
A few years back, most anglers either made their own from 5 gallon buckets or small coolers that would fit in their tankwell. Now, there are bucket and cooler types, plus a fiberglass one and a really nice plastic one, plus some made by kayak manufacturers themselves you just buy and use. We have photos of alot of them in our rigging section here on the site.
The PVC ones you're referring to are bait tubes. Some guys use them, but I haven't made one yet and tried it, so I can't say from any experience. They look like a modified tuna tube which looks like it does about the same thing. Hope this helps, Perry