There exists maps, I beleive, on Rhodium's page that outline the distribution of wild sassafras.
IF you're in such an area, collecting/distilling your own oil is certainly feasable. In the areas where I've found Sassafras, it's literally everywhere in wooded areas - and I mean everywhere. It grows like a weed, and it's not uncommon to find acres upon acres that are abundant in sassafras.
I've never actually seen a sassafras "tree" as it is portrayed on some botanical sites - only as a small weed/shrub. It's very easy to identify. If you live in such an area, your sass is abundant and free (minus your time).