You might have a tough time getting non-absorbable silk unless you know a pharm rep. If I recall the practice sutures that we used as med students was just fishing line (Prolene, PDS, etc). And these are the ones pharm reps bring when sponsoring these sessions, you'll only find the silk in the OR. They also come in pre-made packs with the needle so you would probably have to tie the threads together to get more than a meter or so.