The pricing situation can be irritating, and can depend on many factors, including whether the guy is in a good mood, whether he knows you, etc...I often just decline when I do not like the price (like at any other LFS)
But, in general, I find the prices on the same things fairly consistent from trip to trip. I often guess the exact price before Jos tells me the price (I usually try to deal with Jos).
Most corals are sold by size. 38/48/58 are common prices for small, med, large rocks for common corals.
Some fish as well. I know for a long time their going price for a small-ish achilles tank was either $38 or $48. That was a few years ago, but I could never find one elsewhere for under $100. And yes, it lived.