Most well known online shops don’t seem to have any in stock currently- I’d check out saltwaterfish.com and see if they seem reputable enough for you - they had a few small specimens of three or four species in last night. If you trust Liveaquaria’s current shipping enough, they occasionally get a few in Diver’s Den.
As has been mentioned, there is a very real chance one of your frogfish would eat the other (part of why it’s so rare to see them spawn in captivity).
Typically they don’t live long because of diet is my understanding- lion king (the above poster) has some really good articles on predator food needs. Keeping Magnesium at ~1400 may help with digestion. Appropriately sized live foods are strongly recommended- things like ghost/grass shrimp (Palaemonetes spp.), guppies, and mollies - not things like goldfish (not healthy feed) or crabs (anglers can’t digest the hard shells). As GK3 mentioned, they don’t take well to non-live diets, and even if they start accepting it, keeping the dead diet properly balanced for a predator fish like these is difficult/tedious. Plus, the exercise and mental stimulation of hunting live food is most likely extremely healthy for them.
If you’re planning on splitting the tank between the anglers and clowns, I think you may be hard pressed to fit two anglers in the tank for any length of time without issue (and that’s assuming one doesn’t eat the other) - even small ones. The smallest ones on the
market (and probably the most appropriately sized for what you’re wanting to do) right now are Wartskin Anglers (Antennarius maculatus) and the Pygmy Tuberculated Frogfish (Antennatus tuberosus), and it’s typically recommended that you use a 20 gallon tank (minimum) for one specimen of either.
Plus, as GK3 also mentioned, rearing the larvae in that tank would be incredibly difficult (plus, maintaining a constant food supply for the larvae can be quite challenging whether you’re culturing the feeders yourself or buying them elsewhere).
If you really want to breed these guys, the first thing I’d do is pick up a big tank and ask around for people who have them spawn in their tanks (specifically ask what their feeding routines were and what they think might have helped manage aggression/cannibalism). Beyond that, I’d recommend culturing a variety of feeders (probably Parvocalanus crassirostris pods, S-strain rots, and Isochrysis galbana phyto for the larvae, and ghost shrimp and guppies for the broodstock).
Edit: just wanted to add, I’m glad to see you wanting to give this a go! I’m actually looking at (theoretically) how to keep/breed a few “impossible” species myself once I get my tank up and running (it’ll probably be a little while yet, unfortunately), so I’m glad to see others with similar passion projects.