Those things are awesome IF you're not, um, shall we say "Cartman-esque", like I am. I broke a seat and destroyed a few wheels on the cheaper chairs before I finally just sucked it up and spent the money for a really heavy duty chair from Sears.
Creeper chairs in general are invaluable (IMO) for detailing, though. Grab one; just make sure it'll support you in the long run.
Tort
(Galapagos-sized)
"Damn it, I'm not fat, I'm big-boned!"