To me the price would somewhat depend upon the condition of your ZT set (Kydex marks and, more importantly, the grinds). The ZT's were originally marketed as a bargain Busse, originating when some blanks were mistakenly ground to 3/16" width. As such, they did not exhibit the finest of grinds and finish. I have the letter from Busse Combat that was mailed with the knives, explaining this (thanks, DN).
However, over time, some really fine ZT's came to be made, perfect grinds and finish. For instance, I have two ZT Steel Hearts, one "car knife" and one safe queen. The difference in grinds and finish is striking. One of my first goals when I began to get serious about collecting Busses was to aquire a set of perfect ZT's (perfect grinds, perfect finish, the word Kydex never spoken in their presence). I now have everything but the ZT Satin Jack. The last 30 ZTNO's made are noted for their perfect grinds, but so far, of the ones I have, the most difficult perfect ZT to find was the Steel Heart. Their true value to me right now is much more than what I could sell them for.
Only you can say what their value is to you. But the market price to move them as a set, (going only by what I would pay if I didn't have one) should run from $950 to $1200 or more for the knives, depending on condition, plus a reasonable adder for the sheaths. This is without the Satin Jack, of course.
