I found many of the selections on this mp3 album.
(It has 99 pieces for only $2.49! Sadly, it only has two Songs Without Words, but see below*)
If for some reason this link isn't product specific (I tried!), just type in 99 Mendelssohn and it should come up in the search :)
*Never fear because my compadre Naomi over at Living Charlotte Mason in California has put together a playlist which includes a good selection of aforementioned Songs Without Words on grooveshark - click here.
I'll be posting more on this subject in the weeks to come :)