I got a 48" fixture at my local lowes that has both a cord that you simply plug into an outlet and a on/off switch.I've currently been looking for the same thing - 24" 2 bulb t8 fixture. Home Depot and Lowe's do sell them, but they don't sell anything that can just plug in or with an on/off switch. Everything from those two stores has to be hardwired and turned on with a light switch. They're cheap, under $20, so if you're the DIY kind of person, that would probably work fine. I have absolutely no idea how to wire something like that, so I'm still looking around for something I can plug in.
Chachilla: Is the model you linked to hardwired or a plug-in?