Cheapest possible price to set for a Common SHC Share?

I see this posting which lists the dust threshold of 546 satoshis:

… when Bitcoin SV was forked from ABC, it also inherited Amaury’s moronic dust threshold at 546 satoshis

Based on that, is the minimum SHC share price 547 satoshis (or + few more)?

There is no minimum price. A token txn can add outputs to spend amounts to anyone, so you can control the price paid for shares down to 0 sats and/or 0 fiat tokens. Technically, 546 sats are spent to the output the tokens are received to. This threshold will be lowered to 1 (and possibly 0) when the miners lift that restriction.