Trade has changed since the old guides, but the good news is the new trade is even more profitable, and there are more things that can be profitably traded.
Some of the new ones worth trading:
Raw Silk - Buy in Rivacheg and nearby villages; also buy in villages near Jelkala. Sell in Jelkala and Suno for max profit, but this is one you can sell pretty much anywhere except where you buy it. This now beats Spice as the most profitable per unit item to trade. You can get it for less than 100 and sell for over 700, but a 300-500 spread is more common.
Dyes - Buy in Jelkala and nearby villages; there are some places in Serranid lands that sell it cheap too, but I don't go there much. Buy at below 150 and sell for 190+
Flax - Buy in Praven and some other places, main thing is to sell only in Tihr and Durquba. Buy at 100 or so and sell at 200
Ale - Buy in Praven, sell any number of places. Buy up to 50 and sell down to 100
Grapes - Buy around Tihr, especially the villages. Buy below 40 and sell for 80 or so.
Fur - Buy around Rivacheg, Reyvadin and Khudan and the villages around that area, many places to sell. Buy below 300 and sell for 400 (I go down to 350 if it starts to pile up).
Also a great way to build up quick cash from a small start is the Villages around Dhirim - buy grain cheap and sell at Uxkhal, buy below 10 and sell over 30 - the per unit profit isn't huge but you can make quick money with a very small starting bankroll.
From Tihr you can buy Salt and go the long way to Praven picking up Grapes in the villages and sell in Praven and buy Flax and Ale and then loop back through Suno and Uxkhal through Sargoth and back to Tihr.
Once you have a bankroll you can do the loop Wercheg - Rivacheg - Khudan - Curaw - Reyvadin - Sargoth - Wercheg; if you end up with some extra furs you can find somewhere to sell it not too far.
The main thing is to keep in mind the buy/sell numbers and hit up villages because you can find Furs, Raw Silk, Salt, Iron, Dyes, Grapes, Flax etc in villages at really good prices sometimes. There are really a lot of things that can be traded now - even pottery can make money (buy below 50 and sell for a round 100) but I think you need some trade skill to work that one well.