If you have a Michael's Craft Store near you they have a 32" L x 32" H x 13.5" W wooden slat shelf kit available for holding your terrariums or books or whatever just $5! You couldn't buy the lumber at HD for that. So if you need a new shelf (and who doesn't) take a look. At our local Michael's they were stacked up in a rolling palate sized cart out in front of the store.
I bought one today and will put it together tomorrow if it's sturdy with four 20 High vertical tanks on it I may go buy a few more.
I was getting ready to build a similar shelf but I can't beat $5 and basically already assembled except for a few end screws!
legs can be screwed on the ends of the shelves (giving you all 32" width) or onto the front & back.