I didn't vote as my Betta will murder anything I put in his tank. I'd love to add shrimp but he even tries to kill snails. Bettas are predators in nature. Sometimes one will be extremely laid back and ignore shrimp, but you can never tell until it's too late. My Betta won't flare at a mirror so I would have guessed he would be less aggressive, but I was wrong.
If you're willing to take the risk, I'd go with cherries as they are less expensive. Also Red Crystals need very specific water parameters- unless you already have an active substrate and use purified water with a remineraliser, RCS will not do well in your water.