In all fairness, I doubt you'll find many sellers offering bargain basement prices; this for the following reasons:
EXPENSES: vendors have to pay hundreds of dollars for their booths, and not due to greed or unscrupulous show operators, but for the mere fact that holding an event such as MAX or RAP is UBER EXPENSIVE.
TIME: Transporting livestock to a remote venue, setting up, selling/trading, tearing down, dealing with customers, etc. etc. is extremely taxing on even the most hard-working individual
ECONOMICS: Lets be honest. The reef hobby has created a suedo-ego-driven-trendy-hype as with any other industry. So why would vendor "A" sell frags at $10 each when vendor "B" gets $15 or $20 each? The market dictates prices, not so much the seller
CONVENIENCE: Where else can you find such diverse selection under a single roof, ANYWHERE in the world?
CAMARADERIE: Where else in the world are you given the chance to pick on Gumbii??
SUBSIDIARIES: Food, speakers, raffles, workshops, demonstrations, etc. etc. are all inclusive to the Reef show experience.
Every show has its own unique character, advantages, and disadvantages.
MAX may not draw quite as many visitors, for instance, but we cater to a more family-oriented crowd by design (which carries its own advantages)
MACNA holds a banquet ceremony that neither CA show can even THINK of replicating (it is just too dammn expensive).
CFM reaches niche places in the country that none of the big shows can even think of touching. They do well by hitting much smaller venues.
and then you have the smaller frag swaps that the local clubs host. Many hobbyists have reported liking the old school frag swaps best, so there you have it!
The diversity of choices are there for all to enjoy.