There's no reason you can't add some live plants with the plastic! I've added a few colored plastic plants to my planted tanks for asthetics. My shrimp nibble on the natural plants, but spend time getting the "junk" off the plastic as well. They are so funny to watch! They are good entertainment for inquisitive bettas (and they all are inquisitive to a fault).
There are several good sources foor the red cherry shrimp- ebay, and there's a web site called the Shrimp Farm. I only put the biggest shrimp in w/ the bettas- I have a 1/2 gal for the babies. I've never seen red cherry shrimp in a store; only the ghost/glass shrimp, which don't seem to survive in a tank long, & don't reproduce, either.
4 bettas: Butch, 3-year-old violet male PK EE & 3 girls in a 30 gal sorority. I do not name the girls anymore! 1/2 of them die within a month.
30 gal: 9 Oto cats, 4 Ocellifer cats. Inverts: Cherry shrimp & 2 assasin snails.
10 gal.: Butch, his 5 oto cats, 3 assasin snails, and a few snails the assassins haven't caught.