I wouldn't go for cherry shrimp, pick up a few ghost shrimp first. If he doesn't kill them then look into cherries, but they can go for 5 bucks a pop and the ghost shrimp are like 12 cents each.
I agree and would suggest this period...before you get ANY fish to put in with your Beta.
I obtained a Dwarf Frog thinking they would be fine together, as per suggested...only to get attached to my little Ferggie only to have her die from Blue eating her fingers and picking at her underside. She later died 3 weeks after putting them together [started off good for about a week].
It would be a tragedy to buy nice fish to go with your Beta only for him to kill them when you could have bought a cheap .12 cent shrimp to test it out first. Good luck...and hope your Beta is co-habitable!
Another option you have though if not is to get a divider, IF your tank is large enough. That way you wont have to cycle another tank, but can still have more then one fish.