Hi lemon07r.
Welcome to our Mattress Forum. 
You’re not the first person to pop into the forum with this question. This thread may have some useful information for you.
MFC is one of our Canada based Trusted Members that sells DIY latex components - they could very likely also point you in the direction of coils for your DIY. It’s also worth asking Ken Hightower at Arizona Premium if he has any leads on DIY components in Canada.
I took a look at the mattress you shared and my concern, without knowing your BMI/sleeping position(s) is that they don’t disclose the density of their polyfoam layer - and polyfoam is often a weak link in a mattress. As per our Mattress Durability Guidelines, if you have a BMI of 21 - 30, the density of any polyfoam needs to be at least 1.8 lb per cubic foot or higher.
Is there a particular reason you are looking for a zoned mattress?
Hopefully some of the resources above will be helpful to you. If you have more questions, you are always welcome to ask
NikkiTMU