Basically there are three main branches in the Busse Combat family, which vary in quality of manufacturing (ALWAYS spot-on, though), materials used, and price, although all use the Busse heat-treat. These companies are collectively known as "Bussekin", as they are basically three branches of the same company, Busse.
Busse Combat is the most expensive of the three, and is most widely known, in my opinion. They use INFI steel, have picture-perfect F&F, and most always use micarta scales, although you may get G10, if you like (for a small fee). Busses are also the most expensive, with a wide range of prices, varying from $250 to well over a thousand.
The second in the lineup of Bussekin is SwampRat. SwampRat uses SR-101 steel (for the most part), and uses the Busse heat-treat. They use the same handle materials (again, for the most part) as Busse. Prices for SwampRats vary widely as well, ranging from $50 for a SW neck knife, to around $400 for a RatWaki.
The third is ScrapYard. ScrapYard uses SR-77 steel (though they switch it up, sometimes) with a Busse heat-treat, and they almost exclusively use a handle substance called Res-C. Though I've never handled it myself, the closest I can think of it as is maybe a bicycle inner-tube - extremely grippy, comfortable and soft. ScrapYard's prices range from $50 to around $300.
The other two Bussekins were meant to be a more economical option for those knife enthusiasts who can't pay the arm and a leg for a Busse. Many people swear by SR and SY, and they are nearly as indestructible as Busses, and they all three have that amazing Busse heat-treat, for incredible edge-retention.
As a side-note, no Bussekin comes with a sheath.
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