They design a knife, or two; then put them into a limited production run. When they are gone they are GONE for a few years before being put back into production. If you see one you like you should go ahead and buy it, beats trying to find one in the secondary market. Busse's are fairly priced when sold new from Busse, then the markup begins. Only the marketplace can slow the price from climbing into the stratosphere on some rarer models in high demand from the looks of things. There is a 'list' of the models that have been, and are going into production..... somewhere. Maybe at the top of the Forum?
Once you have fondled a Busse knife you will have no choice but to begin buying every model that catches your eye. The steel has magical qualities, in that it 'looks' so clean and refined you can't help staring at it! I had a passaround Game Warden model that I never took to wood because it was so nice in hand I did'nt want to use it!!
Many folks here have largish collections and multiples of some knives. In order to feed their addiction they often will sell off a 'spare' in order to buy yet another model they want or just came out. You'll eventually end up with one, and be smitten and rolling in the mud with the rest of us here.
On a side note, you can beat the irs if it's a 'book issue'. They came after my family's business one time; but did'nt count on my Mother being the bookkeeper! They owed HER money when SHE was through with THEM!!