Those are nice and clean looking. Pricey though. I bought 6 fans for my two canopies, two adapters, and the wiring to put them all together for just under $60.
I have never seen attachable fans. That is so cool. My electric went out and I had to buy a bubbler battery thing. A battery fan would be perfect for me.
a short comment on fans - I've got a couple of those cheapies on my 125 and they work just fine, but I won a icecap variable speed 4" and put it on my DIY pendent - it is awesome. I was having temp control problems with the MH on a 35 but that fan keeps the tank just right. I think its an issue of how much cooling you need. Those icecaps I see in the catalog are like 60$ - very spendy - but a smaller less effective one wouldn't have worked for me in this application. Its like everything else in this darn hobbie - I think there must be a hole in my wallet, or in my head???