We could probably debate the finer points of the true value of different goods until the cows come home. As there are variations based on set-up and stage of development there won't ever be a catch-all calculation though. Because of all these variations one way or the other I still think trading between any goods somewhere around the 1:1 mark should be acceptable with people having the allowance to trade at different levels if it makes more sense to them. I would imagine that a cap would still be in place because I don't think the game developers wish to allow a bigger player to hand over 100k of goods to a newbie for virtually nothing. Whether that cap was set at 4 times or 16 times or 50 times wouldn't bother me so long as within the cap people could trade as they saw fit and not have the game getting all judgy about it.