A bursa and a huma huma are to similar to put together, I wouldn't do it. If you want to be different, get a assasi trigger from the red sea, similar in appearance and temperament but not something everyone else already has.
As per the "if Joel can get them in at the same time" question, I have them all right now and normally do. The prices were decent on that link you posted Micki but the shipping would kill you. You also would be disappointed in a 2-3 inch O. Niger. Pretty lame when that small and they radically vary in appearance. You will want to pick it out yourself. I'll show you what I mean when you get to the shop today, I have a very pretty Niger in one tank and a boring one in another.
Another concern I have is that most likely the fish you saw on that web sight are going to come from the philipines as cheap as they were selling them. Not only are they typically more bland in color from there, the collection methods are questionable and often they won't have a long life span. The huma huma collected from tropical pacific (Hawaii and similar) are normally much more colorful and very hardy, more expensive though but worth it. Same for the Niger and the rectangle. (also similar to huma huma & bursa but has a very distinct yellow stripe on it) From Hawaii the huma huma may be refered to as a "painted" trigger. The "tiny" clown trigger listed on that site would not be available this time of year, they are out of season being that small and tiny clown triggers often do poorly. Once the hit about 4" or so they seem to be much sturdier. If you get a smaller one and raise it up with eveyone, it'll have much better manners but buy a wild caught larger clown trigger and it can be a major bully!