I didn't try other shops, but at Moonglow tinker boards sell for 6 gold each. Wow. Tinker not going sell many, think normal price around 3 gold. a;]
Re: Biards I would imagine that the 6 gold price is so that there will be a market for player farmed boards. If they sell for 3 gold from shops, a player will be forced to sell at 2-2.5g each, and its just not worth the time when our shard is going to prevent automated/afk farming of those resources.