spectroscopy - Any cheap (

Yes, with a piece of 1000 lines / mm of diffraction grating that costs a few dollars, and some odd bits and ends, you could see the Fraunhofer lines.

Here's a way to build it:

http://sci-toys.com/scitoys/scitoys/light/spectrograph/spectrograph.html

At the bottom there's a link to a place where you could purchase diffraction grating - but any grating around 1000 lines / mm is fine, and you could probably find it in other places too, if this store doesn't work for you for some reason.

You could try to use a digital camera and photograph the spectrum, instead of looking at it directly.

Beware, looking into the Sun poses a certain amount of danger. As long as you keep the slit pretty narrow, this spectrograph is safe. If the spectrum is too bright to look at comfortably, the slit is probably too wide and the instrument is not safe for direct viewing (but probably safe for a camera).

You could also use it to inspect other sources of light: LED lightbulbs, fluorescent lamps, open flames, etc. It's quite fascinating.