Seems that two stock cams (minus 1 bearing) +$75 were traded for 1 stock exhaust cam and two adjustable sprockets.
If you throw the worn cam in the trash, then the net is an intake cam +$75 was traded for 2 adjustable sprockets and a cam bearing.
Assuming the cam bearing is worth $8.57 (made that up) and the used adjustable sprockets are worth $85.39 (made that up too), that is $93.96
Stock gen1 cams aren't going for much at all anymore (complete set just on psychobike for $50), so if we value the intake at $40 and add in the $75, that is $115.
$115 - $93.96= 21.04. Round that UP to a $25 refund and call it a day.