I have seen used sets for one ton trucks go as high as 20,000 for just the tracks. The price is pretty good deal on those tracks if they are the heavy duty ones and the tracks are in good shape it is a smoking deal.
A long time ago I check on new ones and the are friggin expensive.
I found this online
200-M1-A1 $70000 (68000 + $2000 for Steering Assist unit). The 200 series is designed for loaded medium duty trucks such as an F-450 or F-550
175-M1-A1 $40000 The 175 series is for the light end of medium duty or heavy end of light duty trucks. Think F-350 or F-450, perhaps even an F-250 if your planning on really loading it down.
150-M1-A2-SA $36500 Think the medium end of light duty trucks, such as an F-250 or an F-350 (or even the heavy end of the 1/2 ton market if you're planning on loading the truck down).
105-M1-A1 $26500 Think F-150, Expedition, Explorer, even down to the truly light end such as a Jeep.
Pretty good deal looking at it like that, I would guess those are 150s on that van but they could be 175s.
Derek