You're going to get a ton of opinions from people on butterflies. I'd say 9 out of 10 times you need a really mature tank for them to have a shot. Your rock needs to be full of life imo. Captive bred is going to be ridiculously expensive.
There's several things you need to consider.
1) Do you want crustaceans?
2) Are you going to stock heavy or do you want to run low nutrient?
3) is your sand more fine or chunky?
I would stay away from finicky high dollar fish right now.
My suggestions is something like a bicolor angel (dwarf angel), fox face rabbit, ocelaris clown, blenny, dotty back, cardinals, a more peaceful reef safe wrasse, if your sand is more fine then a diamond goby, round it off with anthias or damsels. Maybe scratch the dotty for something that doesn't need as much rockwork.
These fish are fairly easy to find, fairly inexpensive, & hardy. Check out liveaquaria for a selection of things to look at. They have pretty good descriptions of everything then I would go check out local shops. Ordering sw fish online is terrible. The quality of care seems to have just fell off the earth.