You will receive 1-3 goods per FP from most players. Now, normally you will work out with the other player how many FPs you will donate for the number of goods you receive. What the person providing you with the goods is really after is the FPs, so the goods you trade are inconsequential to them, or should be. There is also the actual goods trading, which can be, as you say, your current age goods for the higher era goods, or lower era goods (Bronze, Iron, EMA.) for the higher era goods. There is normally, though not always, a donation of FPs from you to a GB of the person you are dealing with. Generally, you work out a deal with someone that has the goods. I have only seen it once in over 2 years of playing and being in many guilds on multiple worlds. But, like I said, that is extremely rare. That leaves you with only coming up with lower age goods to trade.

If you are really lucky and are in an extremely rare type of guild, you can even find one guildmate who will provide the goods (at 1:2 rates) and another who will pay him the FP cost. I have been offered that for a price of around 350 FP, which is probably around 5 goods per FP. Some guildmates will sell 'packages', such as all the goods for a Traz, for a set price. If you have a friend or guild mate/leader that is more interested in helping the guild grow in this way, you can get better deals. You can also find 1:1.5 and 1:2 ratios fairly easily. I have been quoted as high as 1 FP:5 goods, but that player didn't have any of the goods available, so who knows if he would have actually followed through on that quote. A lot of players that sell the higher age goods as part of their game strategy will charge 1 FP/1 good.

Forge of empires arc goods