Yeah, that 2nd one is kinda what I'm going for except I'm going to mount the sub to fire upward. Then I'll install a drawer set up for tools, straps and so on. Those are both good designs though. Do you know who made them?
You could build that second one for a lot cheaper than $115. One sheet of MDF, a box of staples, bottle of wood glue, tube of caulk, and replacement carpet would cost about $35 and make three of those. I'm currently working one similar to the first one, but with a little more air space. It's about 3/4 put together, just needs a bottom.