SID Sounds Volume 1 is a library of 282 samples (about 32MB unpacked) recorded from an actual Commodore 64. There is the saw, triangle, square, saw-square, triangle-square, and noise. These are single waveform samples and there are not any filter characteristics involved in their sound. Also included in this library are a number of one shot drum samples.
Since so many samples were recorded, there is no stretching done except near the upper and lower octaves. I sampled four octaves worth of notes with most wave forms. The SID never really produces the same exact wave form twice and these little slices will give you that fundamental SID sound. You can listen to a demo here: https://soundcloud.com/pureshift/sets/sid-sounds-demos