Changed my vote on this. Before I stated Do NOT expose prices.
However, having used Naval Action Craft to check shop item prices its bloody useful as a trader to have this available. True, its not very realistic but neither is team chat, nation chat, team speak or email. it doesn't actually provide a massive benefit but is does actually open up the possibility to have some chance of making some reasonable profit. Without it you are not going to bother risking an hour and half sailing ONLY just to get very little return.
In fact I would go as far as to say its vital to give the trading aspect of this game a chance. Even with the data being available I'm finding it very difficult to make good money. By that I mean more or equal to just grinding AI.
Point is - it has not provided to be the huge negative I thought it would have been . It also ensure single players have equal opportunity to those in huge clans.