Any cheap (<100 euro) tools for observing the lines in solar spectrum?
You need a diffraction grating in order to split the sunlight into a spectrum. It turns out even a normal CD or DVD because of the pits that they have to encode data work very well as high resolution diffraction gratings. You could make a simple enclosure with a CD and a slit like this:

http://coolcosmos.ipac.caltech.edu/cosmic_games/spectra/makeGrating.htm

This should allow you to observe the sun's spectrum, although I would also recommend that you be very careful when observing the sun directly. Preferably use a very narrow slit--this will both make it safer and make the absorption lines much clearer.