I've been on the fence for a while with this question myself. I've been considering building my own stackable enclosures for a while, but after researching I'm leaning towards buying them complete.
I've got a few years of carpentry under my belt, but not many of my own tools. So by the time I rent what I need and don't have, plus factor in the cost of materials, then my time it's probably better to just buy.
Keep your eyes on Craigslist. I'm always looking and have kicked myself more than once for not jumping on a good deal on a used enclosure.
Good luck, keep us posted.