The theory is that the Busse shop offers 1 or 2 of their standard models at any one time. You order, with the options you want, and take delivery when the shop finishes them. Depending on demand and how busy they are, expect to wait 6-8 months or more to get your knife. After they run through the 15 or so standard models, they'll start over and offer them all again. (This starting over has not been tested. We're still working our way through the first batch of the "Fusion" models.)
There are several other ways to get knives:
1. Go to a show (Blade, Blade West, Knob Creek for example). You can walk away with your knife the same day, but you have to accept whatever the shop brings.
2. Extravaganzas - These are sales by the Busse shop announced over the internet. There are a few forms. Most often, the knives are already made and whoever emails an order first gets it. Sometimes, the shop accepts orders, and then makes the blades. Expect a few months wait in this case. Either way, knives/orders are gone in seconds to hours.
3. Busse Company Store - This is different from the Busse Shop. They order a few models in relatively large quantities, and take orders on the internet. Knives are in stock and ship immediately. Most blades sell out in minutes to days.
4. Custom Shop - The Busse Shop takes custom orders. I have no experience with this, but expect to pay a few hundred dollars per inch of knife. Long time customers and military units probably have better luck with getting custom orders filled.
5. Buy on the aftermarket. The best source is the Busse Sale region of bladeforums, where people weed out their collections on a regular basis. You'll see the widest range of models here. Other options include eBay and some dealers at shows or on the internet. Somebody even found Busses on Craig's List recently. If you stick around awhile, you'll get to know people and may be able to finagle trades.
Badgers have been shipping lately, and I'd expect some to start appearing on the Bladeforums sale site if you're interested in that model.