The only enclosures I have ever bought are glass aquariums.... they have all since now left my house. I now build all my enclosures to suit the space I have and tailored to each species I keep. This way i can maximise the space and yet provide adequate housing for my reptiles. I have never been a fan of the kit one size fits all..... but hey that's not saying it does'nt work.
Most people down under build their own enclosures and there are more than a few that do it as a business. I have also built some for friends and the one thing I can tell you as a venture to seperate you from the rest is build to the specific species and the specific size limitations of the customer. I say limitations as if you show them how to maximise space. Which means more reptiles for them as well as showing an understanding of their reptiles husbandry needs then mate they'd be lining up for your services. Who does'nt want to fit three enclosures in a space where they thought only one enclosure would fit
Build a couple of "show" peices and the rest build to order this will minimise your capital and save you time.