My honest opinion, you can't really call it an investment, not a return investment, more a one sided investment for your spiders housing needs.
Exo are stunning tanks, they are awesome and if you have the cash, and you only have a couple of spiders you want to house, then why not?
I just feel that they are over priced, it is expensive just for glass and plastic and swing doors, at the end of the day you are paying for the name brand and not the "cage".
You can approach someone who builds tanks and can get the same size tank built for far less.
For the price of the Exo you want, you could get 8 glass tanks built.
But if I read correctly you don't really like the built tanks.
Have you thought about going replica Exo cages, they a bit cheaper, almost look the same.