Customs declaration for things not on goods to follow?
 

My husband will be doing his return trip from the UK in January, and he's got three laptops that he would like to bring with him, but are not on his goods to follow list(his personal laptop and computer are however).

I'm presuming that declaring them is the way to go, but I'm curious as to how he'll be dinged for them. They're in between 8-3 years old, so there not worth near as much as they were new. Anyone have experience with this? He'll also have about 4,000 CAD, but he shouldn't have problems with that right?