Make them yourself.
Go to bunnings and get the melamine pre-cut, drill pilot holes and screw together using chipboard screws.
Things you will need:
-Pre-cut melamine (Bunnings)
-Chipboard screws (Bunnings)
-Glass tracking (Bunnings)
-Either gap filler or silicone to "waterproof" the inside edges (Bunnings)
-2 x Plastic vents (Bunnings)
-2 x pieces of glass per enclosure. (Local glazier) call around as you will be amazed at the price difference.
Regarding the lights I suggest you call a local sparky and offer him a case of his favourite beer to wire the lights (10 minutes work).
Then decide on your heating method. Cords,mats or lights and appropriate fittings like light cages and you are done.
You could probably do all 3 enclosures for the price of a pre built one and making it yourself allows you to customize it to your liking and your needs.