I‘m throwing out a thought here, but I believe the CADPAT, like most of the rest of your issued kit, belongs to the Queen until such time as it is disposed of and declared surplus.
If it belongs to the Queen, then by definition, it doesn‘t belong to you, and you cannot sell it on eBay - because it‘s not yours to sell.
So, following this logic, if it IS sold, it becomes misappropriated ("stolen"). It is illegal to offer anything for sale that is stolen, and it is illegal to purchase anything that is stolen (whether or not you know it is). And, of course, it is illegal to possess anything that has been stolen, or that are proceeds from a crime (such as theft by conversion, fraud, etc).
This goes for any of the kit that has been issued, and that you have not actually purchased from the army.
If I go and sell my kevlar helmet, I would be in four shades of sh!t, because it‘s not mine to sell, and I have to give it back when I leave the army. And anyway, to make it worthwhile, I‘d need to get over $200 for it, because that‘s what the CF will charge me when I don‘t turn it back in.
Would a civilian be prosecuted? Probably not. Unless there is some larger sort of ring involved, the police just don‘t have the resources to devote to a few pairs of CADPAT getting sold on eBay. Then again, maybe the MP‘s _do_ have the time!