Well, a lot depends on what type of light you have. Many of those plants need medium to high light to really look good. What type of lights do you have? Because your tanks are smaller, I'd guess that you have the lights that came with the tanks? THat's probably low light, and most of these plants will not grow well for you.
Here's some low light plants that look great and are super easy to grow:
-Anubias (this is a rhizome plant, only bury roots not tuber). Many types.
-Java Fern (also rhizome, looks great tied on driftwood). May I suggest the 'windelov' variety?
-Cryptocorenes (rooted in the substrate)
-Java moss (a moss, grows like crazy in anything)
-Marimo moss balls (great anti-algae, since it is an algae, just one you want!)
I would not buy a large collection of plants like that just because you could have massive failure and lose all that money. I'd suggest you buy a couple different types of plants, research them, and see how it goes. Best to start small, figure out what your capabilities are, and go from there.
HTH. I may be a noob about bettas, but not about plants!