ArezOne (Honduras) does sound files for the C-152, C-172, C-182, C-185, C-208, C-210, C-337 and C-340.
Synchro-Soft (Germany) has the C-152, C-172, C-182, C-185 and C-208.
SimMarket has them available, most, if not all (didn't check), with a demo video. ArezOne go for about $13 (w/o VAT) while Synchro-Soft are listed at around $7.50 (w/o VAT).
Don't see a C-206 but it used the same engine as the C-185 and Beechcraft Bonanza so either one would probably work.