Sorry it was a little hard to see from the link, but what type of mesh is it on the place where the UVB goes? Is it hardware cloth, with the 1/2" holes, or something more fine than that? If its the hardware cloth, then I would recommend getting the T5 high output fluorescent fixture. It will be able to shine through the hardware cloth down into the enclosure without problem. Just make sure it has a reflector in the fixture.
Or you could make your own enclosure!
Its a lot of fun if you have the tools and the ability, and its a pretty simple design. Alternatively, you could probably put an add on craigslist or something similar for a carpenter that would build it for you. Probably be about the same price as that one you linked to, but without having to move things around or fix them after. Just a thought.